diff --git a/.eslintrc b/.eslintrc
index 3d1bb841..4efde62a 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -6,7 +6,16 @@
         "linebreak-style": ["error", "unix"],
         "max-len": ["error", 120, 4],
         "no-trailing-spaces": ["error", { "skipBlankLines": true }],
-        "no-unused-vars": ["error", {"args": "after-used", "varsIgnorePattern": "^_"}],
+        "no-unused-vars": [
+            "error",
+            {
+                "args": "after-used",
+                # Ignore vars starting with an underscore.
+                "varsIgnorePattern": "^_",
+                # Ignore arguments starting with an underscore.
+                "argsIgnorePattern": "^_"
+            }
+        ],
         "no-use-before-define": ["error"],
         "quotes": ["off"], # Blockly mixes single and double quotes
         "semi": ["error", "always"],
diff --git a/core/tooltip.js b/core/tooltip.js
index 6369c9e0..2e3d3da4 100644
--- a/core/tooltip.js
+++ b/core/tooltip.js
@@ -181,10 +181,10 @@ Blockly.Tooltip.onMouseOver_ = function(e) {
 
 /**
  * Hide the tooltip if the mouse leaves the object and enters the workspace.
- * @param {!Event} e Mouse event.
+ * @param {!Event} _e Mouse event.
  * @private
  */
-Blockly.Tooltip.onMouseOut_ = function(/*e*/) {
+Blockly.Tooltip.onMouseOut_ = function(_e) {
   if (Blockly.Tooltip.blocked_) {
     // Someone doesn't want us to show tooltips.
     return;
diff --git a/core/trashcan.js b/core/trashcan.js
index c5aa411a..a9341311 100644
--- a/core/trashcan.js
+++ b/core/trashcan.js
@@ -171,13 +171,20 @@ Blockly.Trashcan.prototype.createDom = function() {
       {'id': 'blocklyTrashBodyClipPath' + rnd},
       this.svgGroup_);
   Blockly.utils.createSvgElement('rect',
-      {'width': this.WIDTH_, 'height': this.BODY_HEIGHT_,
-       'y': this.LID_HEIGHT_},
+      {
+        'width': this.WIDTH_,
+        'height': this.BODY_HEIGHT_,
+        'y': this.LID_HEIGHT_
+      },
       clip);
   var body = Blockly.utils.createSvgElement('image',
-      {'width': Blockly.SPRITE.width, 'x': -this.SPRITE_LEFT_,
-       'height': Blockly.SPRITE.height, 'y': -this.SPRITE_TOP_,
-       'clip-path': 'url(#blocklyTrashBodyClipPath' + rnd + ')'},
+      {
+        'width': Blockly.SPRITE.width,
+        'x': -this.SPRITE_LEFT_,
+        'height': Blockly.SPRITE.height,
+        'y': -this.SPRITE_TOP_,
+        'clip-path': 'url(#blocklyTrashBodyClipPath' + rnd + ')'
+      },
       this.svgGroup_);
   body.setAttributeNS('http://www.w3.org/1999/xlink', 'xlink:href',
       this.workspace_.options.pathToMedia + Blockly.SPRITE.url);
@@ -188,9 +195,13 @@ Blockly.Trashcan.prototype.createDom = function() {
   Blockly.utils.createSvgElement('rect',
       {'width': this.WIDTH_, 'height': this.LID_HEIGHT_}, clip);
   this.svgLid_ = Blockly.utils.createSvgElement('image',
-      {'width': Blockly.SPRITE.width, 'x': -this.SPRITE_LEFT_,
-       'height': Blockly.SPRITE.height, 'y': -this.SPRITE_TOP_,
-       'clip-path': 'url(#blocklyTrashLidClipPath' + rnd + ')'},
+      {
+        'width': Blockly.SPRITE.width,
+        'x': -this.SPRITE_LEFT_,
+        'height': Blockly.SPRITE.height,
+        'y': -this.SPRITE_TOP_,
+        'clip-path': 'url(#blocklyTrashLidClipPath' + rnd + ')'
+      },
       this.svgGroup_);
   this.svgLid_.setAttributeNS('http://www.w3.org/1999/xlink', 'xlink:href',
       this.workspace_.options.pathToMedia + Blockly.SPRITE.url);
diff --git a/core/ui_menu_utils.js b/core/ui_menu_utils.js
index 740873b3..8fda6021 100644
--- a/core/ui_menu_utils.js
+++ b/core/ui_menu_utils.js
@@ -30,6 +30,7 @@
  **/
 goog.provide('Blockly.utils.uiMenu');
 
+
 /**
  * Get the size of a rendered goog.ui.Menu.
  * @param {!goog.ui.Menu} menu The menu to measure.
diff --git a/core/utils.js b/core/utils.js
index d967325d..b3ba4f45 100644
--- a/core/utils.js
+++ b/core/utils.js
@@ -45,7 +45,7 @@ goog.require('goog.userAgent');
  * accessed through the exact name that was exported. Note, that all the exports
  * are happening as the last thing in the generated js files, so they won't be
  * accessible before JavaScript loads!
- * @return {!Object<string, string>} The message array
+ * @return {!Object.<string, string>} The message array.
  * @private
  */
 Blockly.utils.getMessageArray_ = function() {
@@ -122,7 +122,7 @@ Blockly.utils.removeClass = function(element, className) {
  * @param {!Element} element DOM element to check.
  * @param {string} className Name of class to check.
  * @return {boolean} True if class exists, false otherwise.
- * @private
+ * @package
  */
 Blockly.utils.hasClass = function(element, className) {
   var classes = element.getAttribute('class');
@@ -325,7 +325,7 @@ Blockly.utils.isRightButton = function(e) {
  * @param {!Event} e Mouse event.
  * @param {!Element} svg SVG element.
  * @param {SVGMatrix} matrix Inverted screen CTM to use.
- * @return {!Object} Object with .x and .y properties.
+ * @return {!SVGPoint} Object with .x and .y properties.
  */
 Blockly.utils.mouseToSvg = function(e, svg, matrix) {
   var svgPoint = svg.createSVGPoint();
@@ -451,7 +451,7 @@ Blockly.utils.replaceMessageReferences = function(message) {
   var interpolatedResult = Blockly.utils.tokenizeInterpolation_(message, false);
   // When parseInterpolationTokens == false, interpolatedResult should be at
   // most length 1.
-  return interpolatedResult.length ? interpolatedResult[0] : "";
+  return interpolatedResult.length ? interpolatedResult[0] : '';
 };
 
 /**
diff --git a/core/variable_map.js b/core/variable_map.js
index f517eb71..3451f646 100644
--- a/core/variable_map.js
+++ b/core/variable_map.js
@@ -36,11 +36,11 @@ goog.require('Blockly.VariableModel');
  * @constructor
  */
 Blockly.VariableMap = function(workspace) {
- /**
+  /**
    * A map from variable type to list of variable names.  The lists contain all
    * of the named variables in the workspace, including variables
    * that are not currently in use.
-   * @type {!Object<string, !Array.<Blockly.VariableModel>>}
+   * @type {!Object.<string, !Array.<Blockly.VariableModel>>}
    * @private
    */
   this.variableMap_ = {};
@@ -169,7 +169,7 @@ Blockly.VariableMap.prototype.renameVariableWithConflict_ = function(variable,
  * @param {?string} opt_type The type of the variable like 'int' or 'string'.
  *     Does not need to be unique. Field_variable can filter variables based on
  *     their type. This will default to '' which is a specific type.
- * @param {?string} opt_id The unique id of the variable. This will default to
+ * @param {string=} opt_id The unique ID of the variable. This will default to
  *     a UUID.
  * @return {?Blockly.VariableModel} The newly created variable.
  */
@@ -313,7 +313,7 @@ Blockly.VariableMap.prototype.getVariable = function(name, opt_type) {
 };
 
 /**
- * Find the variable by the given id and return it. Return null if it is not
+ * Find the variable by the given ID and return it. Return null if it is not
  *     found.
  * @param {!string} id The id to check for.
  * @return {?Blockly.VariableModel} The variable with the given id.
@@ -335,7 +335,7 @@ Blockly.VariableMap.prototype.getVariableById = function(id) {
  * Get a list containing all of the variables of a specified type. If type is
  *     null, return list of variables with empty string type.
  * @param {?string} type Type of the variables to find.
- * @return {Array.<Blockly.VariableModel>} The sought after variables of the
+ * @return {!Array.<!Blockly.VariableModel>} The sought after variables of the
  *     passed in type. An empty array if none are found.
  */
 Blockly.VariableMap.prototype.getVariablesOfType = function(type) {
@@ -368,7 +368,7 @@ Blockly.VariableMap.prototype.getVariableTypes = function() {
 
 /**
  * Return all variables of all types.
- * @return {!Array.<Blockly.VariableModel>} List of variable models.
+ * @return {!Array.<!Blockly.VariableModel>} List of variable models.
  */
 Blockly.VariableMap.prototype.getAllVariables = function() {
   var all_variables = [];
diff --git a/core/variable_model.js b/core/variable_model.js
index f60e26ba..453dfa68 100644
--- a/core/variable_model.js
+++ b/core/variable_model.js
@@ -31,14 +31,14 @@ goog.require('goog.string');
 
 /**
  * Class for a variable model.
- * Holds information for the variable including name, id, and type.
+ * Holds information for the variable including name, ID, and type.
  * @param {!Blockly.Workspace} workspace The variable's workspace.
  * @param {!string} name The name of the variable. This must be unique across
  *     each variable type.
  * @param {?string} opt_type The type of the variable like 'int' or 'string'.
  *     Does not need to be unique. Field_variable can filter variables based on
  *     their type. This will default to '' which is a specific type.
- * @param {?string} opt_id The unique id of the variable. This will default to
+ * @param {string=} opt_id The unique ID of the variable. This will default to
  *     a UUID.
  * @see {Blockly.FieldVariable}
  * @constructor
@@ -80,7 +80,7 @@ Blockly.VariableModel = function(workspace, name, opt_type, opt_id) {
 };
 
 /**
- * @return {!string} The id for the variable.
+ * @return {!string} The ID for the variable.
  */
 Blockly.VariableModel.prototype.getId = function() {
   return this.id_;
diff --git a/core/warning.js b/core/warning.js
index 36e365d7..0216c7c7 100644
--- a/core/warning.js
+++ b/core/warning.js
@@ -57,21 +57,27 @@ Blockly.Warning.prototype.collapseHidden = false;
 Blockly.Warning.prototype.drawIcon_ = function(group) {
   // Triangle with rounded corners.
   Blockly.utils.createSvgElement('path',
-      {'class': 'blocklyIconShape',
-       'd': 'M2,15Q-1,15 0.5,12L6.5,1.7Q8,-1 9.5,1.7L15.5,12Q17,15 14,15z'},
-       group);
+      {
+        'class': 'blocklyIconShape',
+        'd': 'M2,15Q-1,15 0.5,12L6.5,1.7Q8,-1 9.5,1.7L15.5,12Q17,15 14,15z'
+      },
+      group);
   // Can't use a real '!' text character since different browsers and operating
   // systems render it differently.
   // Body of exclamation point.
   Blockly.utils.createSvgElement('path',
-      {'class': 'blocklyIconSymbol',
-       'd': 'm7,4.8v3.16l0.27,2.27h1.46l0.27,-2.27v-3.16z'},
-       group);
+      {
+        'class': 'blocklyIconSymbol',
+        'd': 'm7,4.8v3.16l0.27,2.27h1.46l0.27,-2.27v-3.16z'
+      },
+      group);
   // Dot of exclamation point.
   Blockly.utils.createSvgElement('rect',
-      {'class': 'blocklyIconSymbol',
-       'x': '7', 'y': '11', 'height': '2', 'width': '2'},
-       group);
+      {
+        'class': 'blocklyIconSymbol',
+        'x': '7', 'y': '11', 'height': '2', 'width': '2'
+      },
+      group);
 };
 
 /**
@@ -81,11 +87,15 @@ Blockly.Warning.prototype.drawIcon_ = function(group) {
  * @private
  */
 Blockly.Warning.textToDom_ = function(text) {
-  var paragraph = /** @type {!SVGTextElement} */ (
-      Blockly.utils.createSvgElement('text',
-          {'class': 'blocklyText blocklyBubbleText',
-           'y': Blockly.Bubble.BORDER_WIDTH},
-          null));
+  var paragraph = /** @type {!SVGTextElement} */
+      (Blockly.utils.createSvgElement(
+          'text',
+          {
+            'class': 'blocklyText blocklyBubbleText',
+            'y': Blockly.Bubble.BORDER_WIDTH
+          },
+          null)
+      );
   var lines = text.split('\n');
   for (var i = 0; i < lines.length; i++) {
     var tspanElement = Blockly.utils.createSvgElement('tspan',
@@ -136,10 +146,10 @@ Blockly.Warning.prototype.setVisible = function(visible) {
 
 /**
  * Bring the warning to the top of the stack when clicked on.
- * @param {!Event} e Mouse up event.
+ * @param {!Event} _e Mouse up event.
  * @private
  */
-Blockly.Warning.prototype.bodyFocus_ = function(/*e*/) {
+Blockly.Warning.prototype.bodyFocus_ = function(_e) {
   this.bubble_.promote_();
 };
 
diff --git a/core/widgetdiv.js b/core/widgetdiv.js
index 77e04886..408f723b 100644
--- a/core/widgetdiv.js
+++ b/core/widgetdiv.js
@@ -200,7 +200,7 @@ Blockly.WidgetDiv.hideIfOwner = function(oldOwner) {
  * @param {boolean} rtl True if RTL, false if LTR.
  */
 Blockly.WidgetDiv.position = function(anchorX, anchorY, windowSize,
-                                      scrollOffset, rtl) {
+    scrollOffset, rtl) {
   // Don't let the widget go above the top edge of the window.
   if (anchorY < scrollOffset.y) {
     anchorY = scrollOffset.y;
diff --git a/core/workspace.js b/core/workspace.js
index 521ea9c0..f2450baf 100644
--- a/core/workspace.js
+++ b/core/workspace.js
@@ -34,7 +34,7 @@ goog.require('goog.math');
 /**
  * Class for a workspace.  This is a data structure that contains blocks.
  * There is no UI, and can be created headlessly.
- * @param {Blockly.Options} opt_options Dictionary of options.
+ * @param {!Blockly.Options=} opt_options Dictionary of options.
  * @constructor
  */
 Blockly.Workspace = function(opt_options) {
@@ -66,13 +66,13 @@ Blockly.Workspace = function(opt_options) {
 
   /**
    * @type {!Array.<!Blockly.Events.Abstract>}
-   * @private
+   * @protected
    */
   this.undoStack_ = [];
 
   /**
    * @type {!Array.<!Blockly.Events.Abstract>}
-   * @private
+   * @protected
    */
   this.redoStack_ = [];
 
@@ -228,8 +228,8 @@ Blockly.Workspace.prototype.clear = function() {
 /* Begin functions that are just pass-throughs to the variable map. */
 /**
  * Rename a variable by updating its name in the variable map. Identify the
- * variable to rename with the given id.
- * @param {string} id Id of the variable to rename.
+ * variable to rename with the given ID.
+ * @param {string} id ID of the variable to rename.
  * @param {string} newName New variable name.
  */
 Blockly.Workspace.prototype.renameVariableById = function(id, newName) {
@@ -237,13 +237,13 @@ Blockly.Workspace.prototype.renameVariableById = function(id, newName) {
 };
 
 /**
- * Create a variable with a given name, optional type, and optional id.
+ * Create a variable with a given name, optional type, and optional ID.
  * @param {!string} name The name of the variable. This must be unique across
  *     each variable type.
  * @param {?string} opt_type The type of the variable like 'int' or 'string'.
  *     Does not need to be unique. Field_variable can filter variables based on
  *     their type. This will default to '' which is a specific type.
- * @param {?string} opt_id The unique id of the variable. This will default to
+ * @param {string=} opt_id The unique ID of the variable. This will default to
  *     a UUID.
  * @return {?Blockly.VariableModel} The newly created variable.
  */
@@ -261,9 +261,9 @@ Blockly.Workspace.prototype.getVariableUsesById = function(id) {
 };
 
 /**
- * Delete a variables by the passed in id and all of its uses from this
+ * Delete a variables by the passed in ID and all of its uses from this
  * workspace. May prompt the user for confirmation.
- * @param {string} id Id of variable to delete.
+ * @param {string} id ID of variable to delete.
  */
 Blockly.Workspace.prototype.deleteVariableById = function(id) {
   this.variableMap_.deleteVariableById(id);
@@ -283,12 +283,13 @@ Blockly.Workspace.prototype.deleteVariableInternal_ = function(variable, uses) {
 /**
  * Check whether a variable exists with the given name.  The check is
  * case-insensitive.
- * @param {string} name The name to check for.
+ * @param {string} _name The name to check for.
  * @return {number} The index of the name in the variable list, or -1 if it is
  *     not present.
  * @deprecated April 2017
  */
-Blockly.Workspace.prototype.variableIndexOf = function(/* name */) {
+
+Blockly.Workspace.prototype.variableIndexOf = function(_name) {
   console.warn(
       'Deprecated call to Blockly.Workspace.prototype.variableIndexOf');
   return -1;
@@ -308,10 +309,10 @@ Blockly.Workspace.prototype.getVariable = function(name, opt_type) {
 };
 
 /**
- * Find the variable by the given id and return it. Return null if it is not
+ * Find the variable by the given ID and return it. Return null if it is not
  *     found.
- * @param {!string} id The id to check for.
- * @return {?Blockly.VariableModel} The variable with the given id.
+ * @param {!string} id The ID to check for.
+ * @return {?Blockly.VariableModel} The variable with the given ID.
  */
 Blockly.Workspace.prototype.getVariableById = function(id) {
   return this.variableMap_.getVariableById(id);
@@ -362,7 +363,7 @@ Blockly.Workspace.prototype.getWidth = function() {
  * @param {?string} prototypeName Name of the language object containing
  *     type-specific functions for this block.
  * @param {string=} opt_id Optional ID.  Use this ID if provided, otherwise
- *     create a new id.
+ *     create a new ID.
  * @return {!Blockly.Block} The created block.
  */
 Blockly.Workspace.prototype.newBlock = function(prototypeName, opt_id) {
@@ -396,8 +397,7 @@ Blockly.Workspace.prototype.undo = function(redo) {
     for (var i = 0, event; event = events[i]; i++) {
       event.run(redo);
     }
-  }
-  finally {
+  } finally {
     Blockly.Events.recordUndo = true;
   }
 };
diff --git a/core/workspace_audio.js b/core/workspace_audio.js
index 8b746a36..8d0e6e71 100644
--- a/core/workspace_audio.js
+++ b/core/workspace_audio.js
@@ -31,6 +31,7 @@ goog.provide('Blockly.WorkspaceAudio');
  * Class for loading, storing, and playing audio for a workspace.
  * @param {Blockly.WorkspaceSvg} parentWorkspace The parent of the workspace
  *     this audio object belongs to, or null.
+ * @constructor
  */
 Blockly.WorkspaceAudio = function(parentWorkspace) {
 
@@ -107,7 +108,7 @@ Blockly.WorkspaceAudio.prototype.load = function(filenames, name) {
 Blockly.WorkspaceAudio.prototype.preload = function() {
   for (var name in this.SOUNDS_) {
     var sound = this.SOUNDS_[name];
-    sound.volume = .01;
+    sound.volume = 0.01;
     sound.play();
     sound.pause();
     // iOS can only process one sound at a time.  Trying to load more than one
diff --git a/core/workspace_drag_surface_svg.js b/core/workspace_drag_surface_svg.js
index 6309a05a..ad831e51 100644
--- a/core/workspace_drag_surface_svg.js
+++ b/core/workspace_drag_surface_svg.js
@@ -88,13 +88,14 @@ Blockly.WorkspaceDragSurfaceSvg.prototype.createDom = function() {
   *   <g class="blocklyBubbleCanvas">/g>
   * </svg>
   */
-  this.SVG_ = Blockly.utils.createSvgElement('svg', {
-    'xmlns': Blockly.SVG_NS,
-    'xmlns:html': Blockly.HTML_NS,
-    'xmlns:xlink': 'http://www.w3.org/1999/xlink',
-    'version': '1.1',
-    'class': 'blocklyWsDragSurface blocklyOverflowVisible'
-  }, null);
+  this.SVG_ = Blockly.utils.createSvgElement('svg',
+      {
+        'xmlns': Blockly.SVG_NS,
+        'xmlns:html': Blockly.HTML_NS,
+        'xmlns:xlink': 'http://www.w3.org/1999/xlink',
+        'version': '1.1',
+        'class': 'blocklyWsDragSurface blocklyOverflowVisible'
+      }, null);
   this.container_.appendChild(this.SVG_);
 };
 
@@ -110,12 +111,12 @@ Blockly.WorkspaceDragSurfaceSvg.prototype.createDom = function() {
 Blockly.WorkspaceDragSurfaceSvg.prototype.translateSurface = function(x, y) {
   // This is a work-around to prevent a the blocks from rendering
   // fuzzy while they are being moved on the drag surface.
-  x = x.toFixed(0);
-  y = y.toFixed(0);
+  var fixedX = x.toFixed(0);
+  var fixedY = y.toFixed(0);
 
   this.SVG_.style.display = 'block';
-  Blockly.utils.setCssTransform(this.SVG_,
-    'translate3d(' + x + 'px, ' + y + 'px, 0px)');
+  Blockly.utils.setCssTransform(
+      this.SVG_, 'translate3d(' + fixedX + 'px, ' + fixedY + 'px, 0px)');
 };
 
 /**
@@ -131,11 +132,14 @@ Blockly.WorkspaceDragSurfaceSvg.prototype.getSurfaceTranslation = function() {
 /**
  * Move the blockCanvas and bubbleCanvas out of the surface SVG and on to
  * newSurface.
- * @param {!SVGElement} newSurface The element to put the drag surface contents
+ * @param {SVGElement} newSurface The element to put the drag surface contents
  *     into.
  * @package
  */
 Blockly.WorkspaceDragSurfaceSvg.prototype.clearAndHide = function(newSurface) {
+  if (!newSurface) {
+    throw 'Couldn\'t clear and hide the drag surface: missing new surface.';
+  }
   var blockCanvas = this.SVG_.childNodes[0];
   var bubbleCanvas = this.SVG_.childNodes[1];
   if (!blockCanvas || !bubbleCanvas ||
@@ -156,8 +160,8 @@ Blockly.WorkspaceDragSurfaceSvg.prototype.clearAndHide = function(newSurface) {
   Blockly.utils.insertAfter_(bubbleCanvas, blockCanvas);
   // Hide the drag surface.
   this.SVG_.style.display = 'none';
-  goog.asserts.assert(this.SVG_.childNodes.length == 0,
-    'Drag surface was not cleared.');
+  goog.asserts.assert(
+      this.SVG_.childNodes.length == 0, 'Drag surface was not cleared.');
   Blockly.utils.setCssTransform(this.SVG_, '');
   this.previousSibling_ = null;
 };
@@ -168,21 +172,21 @@ Blockly.WorkspaceDragSurfaceSvg.prototype.clearAndHide = function(newSurface) {
  * @param {!Element} blockCanvas The block canvas <g> element from the workspace.
  * @param {!Element} bubbleCanvas The <g> element that contains the bubbles.
  * @param {?Element} previousSibling The element to insert the block canvas &
-       bubble canvas after when it goes back in the dom at the end of a drag.
- * @param {number} width The width of the workspace svg element.
- * @param {number} height The height of the workspace svg element.
+       bubble canvas after when it goes back in the DOM at the end of a drag.
+ * @param {number} width The width of the workspace SVG element.
+ * @param {number} height The height of the workspace SVG element.
  * @param {number} scale The scale of the workspace being dragged.
  * @package
  */
 Blockly.WorkspaceDragSurfaceSvg.prototype.setContentsAndShow = function(
     blockCanvas, bubbleCanvas, previousSibling, width, height, scale) {
-  goog.asserts.assert(this.SVG_.childNodes.length == 0,
-    'Already dragging a block.');
+  goog.asserts.assert(
+      this.SVG_.childNodes.length == 0, 'Already dragging a block.');
   this.previousSibling_ = previousSibling;
   // Make sure the blocks and bubble canvas are scaled appropriately.
   blockCanvas.setAttribute('transform', 'translate(0, 0) scale(' + scale + ')');
-  bubbleCanvas.setAttribute('transform',
-    'translate(0, 0) scale(' + scale + ')');
+  bubbleCanvas.setAttribute(
+      'transform', 'translate(0, 0) scale(' + scale + ')');
   this.SVG_.setAttribute('width', width);
   this.SVG_.setAttribute('height', height);
   this.SVG_.appendChild(blockCanvas);
diff --git a/core/workspace_dragger.js b/core/workspace_dragger.js
index 5c45aab3..09cb9b81 100644
--- a/core/workspace_dragger.js
+++ b/core/workspace_dragger.js
@@ -61,8 +61,8 @@ Blockly.WorkspaceDragger = function(workspace) {
    * @type {!goog.math.Coordinate}
    * @private
    */
-  this.startScrollXY_ = new goog.math.Coordinate(workspace.scrollX,
-        workspace.scrollY);
+  this.startScrollXY_ = new goog.math.Coordinate(
+      workspace.scrollX, workspace.scrollY);
 };
 
 /**
diff --git a/core/workspace_svg.js b/core/workspace_svg.js
index aa646966..007749b6 100644
--- a/core/workspace_svg.js
+++ b/core/workspace_svg.js
@@ -267,7 +267,7 @@ Blockly.WorkspaceSvg.prototype.injectionDiv_ = null;
 /**
  * Map from function names to callbacks, for deciding what to do when a button
  * is clicked.
- * @type {!Object<string, function(!Blockly.FlyoutButton)>}
+ * @type {!Object.<string, function(!Blockly.FlyoutButton)>}
  * @private
  */
 Blockly.WorkspaceSvg.prototype.flyoutButtonCallbacks_ = {};
@@ -275,7 +275,7 @@ Blockly.WorkspaceSvg.prototype.flyoutButtonCallbacks_ = {};
 /**
  * Map from function names to callbacks, for deciding what to do when a custom
  * toolbox category is opened.
- * @type {!Object<string, function(!Blockly.Workspace):!Array<!Element>>}
+ * @type {!Object.<string, function(!Blockly.Workspace):!Array.<!Element>>}
  * @private
  */
 Blockly.WorkspaceSvg.prototype.toolboxCategoryCallbacks_ = {};
@@ -509,7 +509,7 @@ Blockly.WorkspaceSvg.prototype.dispose = function() {
   }
   if (!this.options.parentWorkspace) {
     // Top-most workspace.  Dispose of the div that the
-    // svg is injected into (i.e. injectionDiv).
+    // SVG is injected into (i.e. injectionDiv).
     goog.dom.removeNode(this.getParentSvg().parentNode);
   }
   if (this.resizeHandlerWrapper_) {
@@ -561,7 +561,7 @@ Blockly.WorkspaceSvg.prototype.addZoomControls_ = function(bottom) {
 /**
  * Add a flyout element in an element with the given tag name.
  * @param {string} tagName What type of tag the flyout belongs in.
- * @return {!Element} The element containing the flyout dom.
+ * @return {!Element} The element containing the flyout DOM.
  * @private
  */
 Blockly.WorkspaceSvg.prototype.addFlyout_ = function(tagName) {
@@ -581,7 +581,7 @@ Blockly.WorkspaceSvg.prototype.addFlyout_ = function(tagName) {
   this.flyout_.autoClose = false;
 
   // Return the element  so that callers can place it in their desired
-  // spot in the dom.  For exmaple, mutator flyouts do not go in the same place
+  // spot in the DOM.  For example, mutator flyouts do not go in the same place
   // as main workspace flyouts.
   return this.flyout_.createDom(tagName);
 };
@@ -731,7 +731,7 @@ Blockly.WorkspaceSvg.prototype.translate = function(x, y) {
 
 /**
  * Called at the end of a workspace drag to take the contents
- * out of the drag surface and put them back into the workspace svg.
+ * out of the drag surface and put them back into the workspace SVG.
  * Does nothing if the workspace drag surface is not enabled.
  * @package
  */
@@ -746,7 +746,7 @@ Blockly.WorkspaceSvg.prototype.resetDragSurface = function() {
   var trans = this.workspaceDragSurface_.getSurfaceTranslation();
   this.workspaceDragSurface_.clearAndHide(this.svgGroup_);
   var translation = 'translate(' + trans.x + ',' + trans.y + ') ' +
-        'scale(' + this.scale + ')';
+      'scale(' + this.scale + ')';
   this.svgBlockCanvas_.setAttribute('transform', translation);
   this.svgBubbleCanvas_.setAttribute('transform', translation);
 };
@@ -777,8 +777,8 @@ Blockly.WorkspaceSvg.prototype.setupDragSurface = function() {
   // Figure out where we want to put the canvas back.  The order
   // in the is important because things are layered.
   var previousElement = this.svgBlockCanvas_.previousSibling;
-  var width = this.getParentSvg().getAttribute("width");
-  var height = this.getParentSvg().getAttribute("height");
+  var width = parseInt(this.getParentSvg().getAttribute('width'), 10);
+  var height = parseInt(this.getParentSvg().getAttribute('height'), 10);
   var coord = Blockly.utils.getRelativeXY(this.svgBlockCanvas_);
   this.workspaceDragSurface_.setContentsAndShow(this.svgBlockCanvas_,
       this.svgBubbleCanvas_, previousElement, width, height, this.scale);
@@ -1032,7 +1032,7 @@ Blockly.WorkspaceSvg.prototype.refreshToolboxSelection_ = function() {
 /**
  * Rename a variable by updating its name in the variable map.  Update the
  *     flyout to show the renamed variable immediately.
- * @param {string} id Id of the variable to rename.
+ * @param {string} id ID of the variable to rename.
  * @param {string} newName New variable name.
  * @package
  */
@@ -1044,7 +1044,7 @@ Blockly.WorkspaceSvg.prototype.renameVariableById = function(id, newName) {
 /**
  * Delete a variable by the passed in ID.   Update the flyout to show
  *     immediately that the variable is deleted.
- * @param {string} id Id of variable to delete.
+ * @param {string} id ID of variable to delete.
  * @package
  */
 Blockly.WorkspaceSvg.prototype.deleteVariableById = function(id) {
@@ -1059,7 +1059,7 @@ Blockly.WorkspaceSvg.prototype.deleteVariableById = function(id) {
  * @param {string=} opt_type The type of the variable like 'int' or 'string'.
  *     Does not need to be unique. Field_variable can filter variables based on
  *     their type. This will default to '' which is a specific type.
- * @param {string=} opt_id The unique id of the variable. This will default to
+ * @param {string=} opt_id The unique ID of the variable. This will default to
  *     a UUID.
  * @return {?Blockly.VariableModel} The newly created variable.
  * @package
@@ -1584,6 +1584,7 @@ Blockly.WorkspaceSvg.prototype.zoomToFit = function() {
 Blockly.WorkspaceSvg.prototype.scrollCenter = function() {
   if (!this.scrollbar) {
     // Can't center a non-scrolling workspace.
+    console.warn('Tried to scroll a non-scrollable workspace.');
     return;
   }
   // Hide the WidgetDiv without animation (zoom makes field out of place with div)
@@ -1752,7 +1753,7 @@ Blockly.WorkspaceSvg.getContentDimensionsExact_ = function(ws) {
 Blockly.WorkspaceSvg.getContentDimensionsBounded_ = function(ws, svgSize) {
   var content = Blockly.WorkspaceSvg.getContentDimensionsExact_(ws);
 
-  // View height and width are both in pixels, and are the same as the svg size.
+  // View height and width are both in pixels, and are the same as the SVG size.
   var viewWidth = svgSize.width;
   var viewHeight = svgSize.height;
   var halfWidth = viewWidth / 2;
@@ -1968,7 +1969,7 @@ Blockly.WorkspaceSvg.prototype.removeButtonCallback = function(key) {
  * custom toolbox categories in this workspace.  See the variable and procedure
  * categories as an example.
  * @param {string} key The name to use to look up this function.
- * @param {function(!Blockly.Workspace):!Array<!Element>} func The function to
+ * @param {function(!Blockly.Workspace):!Array.<!Element>} func The function to
  *     call when the given toolbox category is opened.
  */
 Blockly.WorkspaceSvg.prototype.registerToolboxCategoryCallback = function(key,
@@ -1982,7 +1983,7 @@ Blockly.WorkspaceSvg.prototype.registerToolboxCategoryCallback = function(key,
  * Get the callback function associated with a given key, for populating
  * custom toolbox categories in this workspace.
  * @param {string} key The name to use to look up the function.
- * @return {?function(!Blockly.Workspace):!Array<!Element>} The function
+ * @return {?function(!Blockly.Workspace):!Array.<!Element>} The function
  *     corresponding to the given key for this workspace, or null if no function
  *     is registered.
  */
diff --git a/core/xml.js b/core/xml.js
index 9faf9640..a407ce94 100644
--- a/core/xml.js
+++ b/core/xml.js
@@ -38,7 +38,7 @@ goog.require('goog.userAgent');
 /**
  * Encode a block tree as XML.
  * @param {!Blockly.Workspace} workspace The workspace containing blocks.
- * @param {boolean} opt_noId True if the encoder should skip the block ids.
+ * @param {boolean=} opt_noId True if the encoder should skip the block IDs.
  * @return {!Element} XML document.
  */
 Blockly.Xml.workspaceToDom = function(workspace, opt_noId) {
@@ -71,7 +71,7 @@ Blockly.Xml.variablesToDom = function(variableList) {
 /**
  * Encode a block subtree as XML with XY coordinates.
  * @param {!Blockly.Block} block The root block to encode.
- * @param {boolean} opt_noId True if the encoder should skip the block id.
+ * @param {boolean=} opt_noId True if the encoder should skip the block ID.
  * @return {!Element} Tree of XML elements.
  */
 Blockly.Xml.blockToDomWithXY = function(block, opt_noId) {
@@ -165,7 +165,7 @@ Blockly.Xml.allFieldsToDom_ = function(block, element) {
 /**
  * Encode a block subtree as XML.
  * @param {!Blockly.Block} block The root block to encode.
- * @param {boolean} opt_noId True if the encoder should skip the block id.
+ * @param {boolean=} opt_noId True if the encoder should skip the block ID.
  * @return {!Element} Tree of XML elements.
  */
 Blockly.Xml.blockToDom = function(block, opt_noId) {
@@ -379,7 +379,7 @@ Blockly.Xml.clearWorkspaceAndLoadFromXml = function(xml, workspace) {
  * Decode an XML DOM and create blocks on the workspace.
  * @param {!Element} xml XML DOM.
  * @param {!Blockly.Workspace} workspace The workspace.
- * @return {Array.<string>} An array containing new block ids.
+ * @return {Array.<string>} An array containing new block IDs.
  */
 Blockly.Xml.domToWorkspace = function(xml, workspace) {
   if (xml instanceof Blockly.Workspace) {
@@ -393,7 +393,7 @@ Blockly.Xml.domToWorkspace = function(xml, workspace) {
   if (workspace.RTL) {
     width = workspace.getWidth();
   }
-  var newBlockIds = []; // A list of block ids added by this call.
+  var newBlockIds = [];  // A list of block IDs added by this call.
   Blockly.Field.startCache();
   // Safari 7.1.3 is known to provide node lists with extra references to
   // children beyond the lists' length.  Trust the length, do not use the
@@ -420,8 +420,10 @@ Blockly.Xml.domToWorkspace = function(xml, workspace) {
         // to be moved to a nested destination in the next operation.
         var block = Blockly.Xml.domToBlock(xmlChild, workspace);
         newBlockIds.push(block.id);
-        var blockX = parseInt(xmlChild.getAttribute('x'), 10);
-        var blockY = parseInt(xmlChild.getAttribute('y'), 10);
+        var blockX = xmlChild.hasAttribute('x') ?
+            parseInt(xmlChild.getAttribute('x'), 10) : 10;
+        var blockY = xmlChild.hasAttribute('y') ?
+            parseInt(xmlChild.getAttribute('y'), 10) : 10;
         if (!isNaN(blockX) && !isNaN(blockY)) {
           block.moveBy(workspace.RTL ? width - blockX : blockX, blockY);
         }
@@ -429,11 +431,10 @@ Blockly.Xml.domToWorkspace = function(xml, workspace) {
       } else if (name == 'shadow') {
         goog.asserts.fail('Shadow block cannot be a top-level block.');
         variablesFirst = false;
-      }  else if (name == 'variables') {
+      } else if (name == 'variables') {
         if (variablesFirst) {
           Blockly.Xml.domToVariables(xmlChild, workspace);
-        }
-        else {
+        } else {
           throw Error('\'variables\' tag must exist once before block and ' +
             'shadow tag elements in the workspace XML, but it was found in ' +
             'another location.');
@@ -441,8 +442,7 @@ Blockly.Xml.domToWorkspace = function(xml, workspace) {
         variablesFirst = false;
       }
     }
-  }
-  finally {
+  } finally {
     if (!existingGroup) {
       Blockly.Events.setGroup(false);
     }
@@ -460,12 +460,12 @@ Blockly.Xml.domToWorkspace = function(xml, workspace) {
  * blocks immediately below prior blocks, aligned by their starting edge.
  * @param {!Element} xml The XML DOM.
  * @param {!Blockly.Workspace} workspace The workspace to add to.
- * @return {Array.<string>} An array containing new block ids.
+ * @return {Array.<string>} An array containing new block IDs.
  */
 Blockly.Xml.appendDomToWorkspace = function(xml, workspace) {
-  var bbox; //bounding box of the current blocks
-  // first check if we have a workspaceSvg otherwise the block have no shape
-  // and the position does not matter
+  var bbox;  // Bounding box of the current blocks.
+  // First check if we have a workspaceSvg, otherwise the blocks have no shape
+  // and the position does not matter.
   if (workspace.hasOwnProperty('scale')) {
     var savetab = Blockly.BlockSvg.TAB_WIDTH;
     try {
@@ -475,7 +475,7 @@ Blockly.Xml.appendDomToWorkspace = function(xml, workspace) {
       Blockly.BlockSvg.TAB_WIDTH = savetab;
     }
   }
-  // load the new blocks into the workspace and get the ids of the new blocks
+  // Load the new blocks into the workspace and get the IDs of the new blocks.
   var newBlockIds = Blockly.Xml.domToWorkspace(xml,workspace);
   if (bbox && bbox.height) { // check if any previous block
     var offsetY = 0; // offset to add to y of the new block
@@ -566,7 +566,7 @@ Blockly.Xml.domToBlock = function(xmlBlock, workspace) {
     var newVariables = Blockly.Variables.getAddedVariables(workspace,
         variablesBeforeCreation);
     // Fire a VarCreate event for each (if any) new variable created.
-    for(var i = 0; i < newVariables.length; i++) {
+    for (var i = 0; i < newVariables.length; i++) {
       var thisVariable = newVariables[i];
       Blockly.Events.fire(new Blockly.Events.VarCreate(thisVariable));
     }
@@ -607,8 +607,8 @@ Blockly.Xml.domToVariables = function(xmlVariables, workspace) {
 Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
   var block = null;
   var prototypeName = xmlBlock.getAttribute('type');
-  goog.asserts.assert(prototypeName, 'Block type unspecified: %s',
-                      xmlBlock.outerHTML);
+  goog.asserts.assert(
+      prototypeName, 'Block type unspecified: %s', xmlBlock.outerHTML);
   var id = xmlBlock.getAttribute('id');
   block = workspace.newBlock(prototypeName, id);
 
@@ -731,7 +731,7 @@ Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
   }
   var disabled = xmlBlock.getAttribute('disabled');
   if (disabled) {
-    block.setDisabled(disabled == 'true');
+    block.setDisabled(disabled == 'true' || disabled == 'disabled');
   }
   var deletable = xmlBlock.getAttribute('deletable');
   if (deletable) {
@@ -753,8 +753,8 @@ Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
     // Ensure all children are also shadows.
     var children = block.getChildren();
     for (var i = 0, child; child = children[i]; i++) {
-      goog.asserts.assert(child.isShadow(),
-                          'Shadow block not allowed non-shadow child.');
+      goog.asserts.assert(
+          child.isShadow(), 'Shadow block not allowed non-shadow child.');
     }
     block.setShadow(true);
   }