bindings: Fixes layouttests when moving attributes to prototype chains.

LayoutTests/http/tests/w3c/webperf/resources/worker.js

 function runTests(event) {
   var tests = event.data;
   var results = [];
   for (var i = 0; i < tests.length; i++) {
     try {
       results.push(eval(tests[i]));
     } catch(e) {
       results.push(e);
     }
   }
   return results;
 }
 
 self.onmessage = function(event) {
   var results = runTests(event);
   postMessage(results);
   self.close();
 };
 
 self.addEventListener("connect", function(event) {
   var port = event.ports[0];
   port.onmessage = function(event) {
     var results = runTests(event);
     port.postMessage(results);
   };
 });
+
+// Stringifies a DOM object.  This function stringifies not only own properties
+// but also DOM attributes which are on a prototype chain.  Note that
+// JSON.stringify only stringifies own properties.
+function stringifyDOMObject(domObject) {
+  var object = {};
+  for (var property in domObject) {
+    object[property] = domObject[property];
+  }
+  return JSON.stringify(object);
+}