DevTools: ignore weak referenced when calculating dominators for heap snapshot

LayoutTests/inspector/profiler/heap-snapshot-test.js

 var initialize_HeapSnapshotTest = function() {
 
 InspectorTest.preloadPanel("profiles");
 
 InspectorTest.createHeapSnapshotMockFactories = function() {
 
 InspectorTest.createJSHeapSnapshotMockObject = function()
 {
     return {
         _rootNodeIndex: 0,
@@ skipping 243 matching lines @@
         rawSnapshot.edges.push(this._targetNode._ordinal * builder.nodeFieldsCount); // index
     }
 }
 
 InspectorTest.HeapEdge.Type = {
     "context": "context",
     "element": "element",
     "property": "property",
     "internal": "internal",
     "hidden": "hidden",
-    "shortcut": "shortcut"
+    "shortcut": "shortcut",
+    "weak": "weak"
 };
 
 InspectorTest.HeapSnapshotBuilder = function()
 {
     this._nodes = [];
     this._string2id = {};
     this._strings = [];
     this.nodeFieldsCount = 7;
 
     this._nodeTypesMap = {};
@@ skipping 453 matching lines @@
         function sortingComplete()
         {
             dataGrid.removeEventListener(WebInspector.HeapSnapshotSortableDataGrid.Events.SortingComplete, sortingComplete, null);
             callback();
         }
         dataGrid.addEventListener(WebInspector.HeapSnapshotSortableDataGrid.Events.SortingComplete, sortingComplete, null);
     }
 };
 
 };