bindings: Fixes layouttests when moving attributes to prototype chains.

LayoutTests/fast/dom/script-tests/webtiming-navigate-within-document.js

 description("This test checks that navigating within the document does not reset Web Timing numbers.");
 
 window.performance = window.performance || {};
 var timing = performance.timing || {};
 
 function checkTimingNotChanged()
 {
-    properties = Object.keys(timing).sort();
+    var properties = [];
+    for (var property in timing) {
+        properties.push(property);
+    }
+    properties.sort();
     for (var i = 0; i < properties.length; ++i) {
-        property = properties[i];
+        var property = properties[i];
         if (timing[property] === initialTiming[property])
             testPassed(property + " is unchanged.");
         else
             testFailed(property + " changed.");
     }
     finishJSTest();
 }
 
 var initialTiming = {};
 function saveTimingAfterLoad()
 {
     for (var property in timing) {
         initialTiming[property] = timing[property];
     }
     window.location.href = "#1";
     setTimeout("checkTimingNotChanged()", 0);
 }
 
 function loadHandler()
 {
     window.removeEventListener("load", loadHandler);
     setTimeout("saveTimingAfterLoad()", 0);
 }
 window.addEventListener("load", loadHandler, false);
 
 jsTestIsAsync = true;