Devtools: make DOM traversal utilities climb shadow tree.

Source/devtools/front_end/layers/LayerTreeOutline.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 114 matching lines @@
                 node = nextNode;
             }
         }
     },
 
     /**
      * @param {!Event} event
      */
     _onMouseMove: function(event)
     {
-        var node = this._treeOutline.treeElementFromPoint(event.pageX, event.pageY);
+        var node = this._treeOutline.treeElementFromEvent(event);
         if (node === this._lastHoveredNode)
             return;
         this.dispatchEventToListeners(WebInspector.LayerTreeOutline.Events.LayerHovered, node && node.representedObject ? {layer: node.representedObject} : null);
     },
 
     /**
      * @param {!WebInspector.LayerTreeElement} node
      */
     _selectedNodeChanged: function(node)
     {
         var layer = /** @type {!WebInspector.Layer} */ (node.representedObject);
         this.dispatchEventToListeners(WebInspector.LayerTreeOutline.Events.LayerSelected, {layer: layer});
     },
 
     /**
      * @param {!Event} event
      */
     _onContextMenu: function(event)
     {
-        var node = this._treeOutline.treeElementFromPoint(event.pageX, event.pageY);
+        var node = this._treeOutline.treeElementFromEvent(event);
         if (!node || !node.representedObject)
             return;
         var layer = /** @type {!WebInspector.Layer} */ (node.representedObject);
         if (!layer)
             return;
         var domNode = layer.nodeForSelfOrAncestor();
         if (!domNode)
             return;
         var contextMenu = new WebInspector.ContextMenu(event);
         contextMenu.appendApplicableItems(domNode);
@@ skipping 49 matching lines @@
     /**
      * @param {boolean} hovered
      */
     setHovered: function(hovered)
     {
         this.listItemElement.classList.toggle("hovered", hovered);
     },
 
     __proto__: TreeElement.prototype
 }