Instrument DomDistiller with timing information.

src/com/dom_distiller/client/DomUtil.java

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package com.dom_distiller.client;
 
 import com.google.gwt.core.client.JsArray;
 import com.google.gwt.dom.client.Element;
 import com.google.gwt.dom.client.Node;
 import com.google.gwt.dom.client.NodeList;
@@ skipping 78 matching lines @@
     public static String getInnerText(Node node) {
         String text = javascriptInnerText(node);
         if (text != null) return text;
         return node.getNodeType() == Node.ELEMENT_NODE ? Element.as(node).getInnerText() : "";
     }
 
     private static native String javascriptInnerText(Node node) /*-{
         return node.innerText;
     }-*/;
 
+    public static native double getTime() /*-{
+        // window.performance is unavailable in Gwt's dev environment.
+        return window.performance ? window.performance.now() : 0;
+    }-*/;
+
     /**
      * Use jsni for direct access to javascript's textContent.  textContent is different from
      * innerText (see http://www.kellegous.com/j/2013/02/27/innertext-vs-textcontent):
      * - textContent is the raw textual content, doesn't require layout, and is basically a
      *   concatenation of the values of all text nodes within a subtree.
      * - innerText is what is presented to the user, requires layout, and excludes text in invisible
      *   elements, e.g. <title> tags.
      */
     public static native String javascriptTextContent(Node node) /*-{
         return node.textContent;
     }-*/;
 }