Use src/index as browser entry point

Use src/index.js as the entry by default in tools building scratch-vm
into a larger package. This saves file space by excluding extra webpack
boilerplate and may allow for deeper optimizations.

Depend on script dependencies for downstream webpack. For another
package to build in scratch-vm's dependencies without them already
being built into a consumed webpack build they need to be listed as
dependencies. This can benefit large projects that reuse the same
dependencies multiple times. Node will still use the main entry point
and its webpack build leaves the dependencies as external references so
it may reuse common modules in Node as well as in a build a browser
environment.

package.json

@@ -10,7 +10,7 @@
     "url": "git+ssh://git@github.com/LLK/scratch-vm.git"
   },
   "main": "./dist/node/scratch-vm.js",
-  "browser": "./dist/web/scratch-vm.js",
+  "browser": "./src/index.js",
   "scripts": {
     "build": "webpack --progress --colors --bail",
     "coverage": "tap ./test/{unit,integration}/*.js --coverage --coverage-report=lcov",
@@ -27,6 +27,22 @@
     "watch": "webpack --progress --colors --watch",
     "version": "json -f package.json -I -e \"this.repository.sha = '$(git log -n1 --pretty=format:%H)'\""
   },
+  "dependencies": {
+    "arraybuffer-loader": "^1.0.3",
+    "decode-html": "2.0.0",
+    "diff-match-patch": "1.0.0",
+    "escape-html": "1.0.3",
+    "format-message": "5.2.1",
+    "htmlparser2": "3.9.2",
+    "immutable": "3.8.1",
+    "jszip": "^3.1.5",
+    "minilog": "3.1.0",
+    "nets": "3.2.0",
+    "scratch-parser": "4.1.1",
+    "socket.io-client": "2.0.4",
+    "text-encoding": "0.6.4",
+    "worker-loader": "^1.1.1"
+  },
   "devDependencies": {
     "adm-zip": "0.4.7",
     "arraybuffer-loader": "^1.0.3",
@@ -36,42 +52,27 @@
     "babel-preset-env": "^1.6.1",
     "canvas-toBlob": "1.0.0",
     "copy-webpack-plugin": "^4.5.1",
-    "decode-html": "2.0.0",
-    "diff-match-patch": "1.0.0",
-    "escape-html": "1.0.3",
     "eslint": "^4.5.0",
     "eslint-config-scratch": "^5.0.0",
     "expose-loader": "0.7.5",
     "file-loader": "^1.1.6",
-    "format-message": "5.2.1",
     "format-message-cli": "5.2.1",
     "gh-pages": "^1.1.0",
-    "highlightjs": "^9.8.0",
-    "htmlparser2": "3.9.2",
-    "immutable": "3.8.1",
     "in-publish": "^2.0.0",
     "json": "^9.0.4",
-    "jszip": "^3.1.5",
     "lodash.defaultsdeep": "4.6.0",
-    "minilog": "3.1.0",
-    "nets": "3.2.0",
     "pngjs": "^3.3.2",
-    "promise": "8.0.1",
     "scratch-audio": "latest",
     "scratch-blocks": "latest",
-    "scratch-parser": "4.1.1",
     "scratch-render": "latest",
     "scratch-storage": "^0.4.0",
     "scratch-translate-extension-languages": "0.0.20180521154850",
     "script-loader": "0.7.2",
-    "socket.io-client": "2.0.4",
     "stats.js": "^0.17.0",
     "tap": "^11.0.1",
-    "text-encoding": "0.6.4",
     "tiny-worker": "^2.1.1",
     "webpack": "^4.8.0",
     "webpack-cli": "^2.0.15",
-    "webpack-dev-server": "^3.1.3",
-    "worker-loader": "^1.1.1"
+    "webpack-dev-server": "^3.1.3"
   }
 }

src/playground/index.html

@@ -79,7 +79,7 @@
 
   <div id="blocks"></div>
 
-  <!-- FPS counter, Syntax highlighter, Blocks, Renderer -->
+  <!-- FPS counter, Blocks, Renderer -->
   <script src="./vendor.js"></script>
   <!-- Storage module -->
   <script src="./scratch-storage.js"></script>

webpack.config.js

@@ -69,6 +69,19 @@ module.exports = [
         output: {
             libraryTarget: 'commonjs2',
             path: path.resolve('dist', 'node')
+        },
+        externals: {
+            'decode-html': true,
+            'escape-html': true,
+            'format-message': true,
+            'htmlparser2': true,
+            'immutable': true,
+            'jszip': true,
+            'minilog': true,
+            'nets': true,
+            'scratch-parser': true,
+            'socket.io-client': true,
+            'text-encoding': true
         }
     }),
     // Playground
@@ -79,8 +92,6 @@ module.exports = [
             'vendor': [
                 // FPS counter
                 'stats.js/build/stats.min.js',
-                // Syntax highlighter
-                'highlightjs/highlight.pack.min.js',
                 // Scratch Blocks
                 'scratch-blocks/dist/vertical.js',
                 // Audio
@@ -139,8 +150,6 @@ module.exports = [
             new CopyWebpackPlugin([{
                 from: 'node_modules/scratch-blocks/media',
                 to: 'media'
-            }, {
-                from: 'node_modules/highlightjs/styles/zenburn.css'
             }, {
                 from: 'node_modules/scratch-storage/dist/web'
             }, {