bindings: Fixes layouttests when moving attributes to prototype chains.

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

Index: LayoutTests/http/tests/w3c/webperf/resources/worker.js
diff --git a/LayoutTests/http/tests/w3c/webperf/resources/worker.js b/LayoutTests/http/tests/w3c/webperf/resources/worker.js
index 1e3e58cf692c72c346a590c6e3b58572a8ea6882..610c8eb731c2cc362199e46e84869450d60153cf 100644
--- a/LayoutTests/http/tests/w3c/webperf/resources/worker.js
+++ b/LayoutTests/http/tests/w3c/webperf/resources/worker.js
@@ -24,3 +24,14 @@ self.addEventListener("connect", function(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);
+}