Properly handle generated IDs in SVG export.

Closes #1138

src/svg/SvgExport.js

@@ -326,8 +326,8 @@ new function() {
             definitions = { ids: {}, svgs: {} };
         // Use #__id for items that don't have internal #_id properties (Color),
         // and give them ids from their own private id pool named 'svg'.
-        var id = item._id || item.__id || (item.__id = UID.get('svg'));
-        return item && definitions.svgs[type + '-' + id];
+        return item && definitions.svgs[type + '-'
+                + (item._id || item.__id || (item.__id = UID.get('svg')))];
     }
 
     function setDefinition(item, node, type) {

test/helpers.js

@@ -217,11 +217,9 @@ var comparePixels = function(actual, expected, message, options) {
         var tolerance = (options.tolerance || 1e-4) * 100,
             fixed = tolerance < 1 ? ((1 / tolerance) + '').length - 1 : 0,
             identical = result ? 100 - result.misMatchPercentage : 0,
-            reached = identical.toFixed(fixed),
-            hundred = (100).toFixed(fixed),
-            ok = reached == hundred,
-            text = reached + '% identical';
-        QUnit.push(ok, text, hundred + '% identical', message);
+            ok = Math.abs(100 - identical) <= tolerance,
+            text = identical.toFixed(fixed) + '% identical';
+        QUnit.push(ok, text, (100).toFixed(fixed) + '% identical', message);
         if (!ok && result && !isNode) {
             // Get the right entry for this unit test and assertion, and
             // replace the results with images

test/tests/SvgExport.js

@@ -191,4 +191,25 @@ if (!isNode) {
             tolerance: 1e-2
         });
     });
+
+    test('Export SVG with clipping defs', function(assert) {
+        var group = new Group({
+            children: [
+                new Path.Circle({
+                    center: [150, 150],
+                    radius: 50
+                }),
+                new Path.Rectangle({
+                    point: [100, 100],
+                    size: [100, 100],
+                    fillColor: 'green'
+                })
+            ],
+            clipped: true
+        });
+        var svg = project.exportSVG({ bounds: 'content', asString: true });
+        compareSVG(assert.async(), svg, project.activeLayer, null, {
+            tolerance: 1e-2
+        });
+    });
 }