Devtools: make DOM traversal utilities climb shadow tree.

Source/devtools/front_end/layers/LayerTreeOutline.js

Index: Source/devtools/front_end/layers/LayerTreeOutline.js
diff --git a/Source/devtools/front_end/layers/LayerTreeOutline.js b/Source/devtools/front_end/layers/LayerTreeOutline.js
index c8b0dbcf0b8fbe0eb7e7204bdcfc19622497c4c5..0c38ab006288602e4b7d9801df75e6f31e1a56b1 100644
--- a/Source/devtools/front_end/layers/LayerTreeOutline.js
+++ b/Source/devtools/front_end/layers/LayerTreeOutline.js
@@ -132,7 +132,7 @@ WebInspector.LayerTreeOutline.prototype = {
      */
     _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);
@@ -152,7 +152,7 @@ WebInspector.LayerTreeOutline.prototype = {
      */
     _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);