Devtools: make DOM traversal utilities climb shadow tree.

Source/devtools/front_end/ui/treeoutline.js

Index: Source/devtools/front_end/ui/treeoutline.js
diff --git a/Source/devtools/front_end/ui/treeoutline.js b/Source/devtools/front_end/ui/treeoutline.js
index 92b4e610c062a68b10b65a7813562e2b122e01c0..b613d69b214e989d69545f376a9ad753f788c078 100644
--- a/Source/devtools/front_end/ui/treeoutline.js
+++ b/Source/devtools/front_end/ui/treeoutline.js
@@ -323,7 +323,7 @@ TreeOutline.prototype.findTreeElement = function(representedObject, getParent)
  */
 TreeOutline.prototype.treeElementFromPoint = function(x, y)
 {
-    var node = this._childrenListNode.ownerDocument.elementFromPoint(x, y);
+    var node = this._childrenListNode.ownerDocument.deepElementFromPoint(x, y);
     if (!node)
         return null;
 
@@ -333,6 +333,15 @@ TreeOutline.prototype.treeElementFromPoint = function(x, y)
     return null;
 }
 
+/**
+ * @param {?Event} event
+ * @return {?TreeElement}
+ */
+TreeOutline.prototype.treeElementFromEvent = function(event)
+{
+    return event ? this.treeElementFromPoint(event.pageX, event.pageY) : null;
+}
+
 TreeOutline.prototype._treeKeyDown = function(event)
 {
     if (event.target !== this._childrenListNode)