bindings: Fixes layouttests when moving attributes to prototype chains.

LayoutTests/resources/js-test.js

Index: LayoutTests/resources/js-test.js
diff --git a/LayoutTests/resources/js-test.js b/LayoutTests/resources/js-test.js
index 10abf0bc336b48f85c4658e6af7efd4818a7443b..392762a980693d8de147483d8db9453c3610ae56 100644
--- a/LayoutTests/resources/js-test.js
+++ b/LayoutTests/resources/js-test.js
@@ -199,6 +199,23 @@ function stringify(v)
     else return "" + v;
 }
 
+// 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(object)
+{
+    function deepCopy(src) {
+        if (typeof src != "object")
+            return src;
+        var dst = src instanceof Array ? [] : {};

[jsbell, 2015/01/21 18:09:39]

Nit: Use Array.isArray()

(instanceof doesn't work across 'realms')

[Yuki, 2015/01/22 06:53:29]

Done.

+        for (var property in src) {
+            dst[property] = deepCopy(src[property]);
+        }
+        return dst;
+    }
+    return JSON.stringify(deepCopy(object));
+}
+
 function evalAndLog(_a, _quiet)
 {
   if (typeof _a != "string")