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..e4d56e4256eeb46c2152ed6dff9559d1c84d6e05 100644
--- a/LayoutTests/resources/js-test.js
+++ b/LayoutTests/resources/js-test.js
@@ -190,6 +190,16 @@ function isResultCorrect(actual, expected)
     return false;
 }
 
+// Returns a sorted array of property names of object.  This function returns
+// not only own properties but also properties on prototype chains.
+function getAllPropertyNames(object) {
+    var properties = [];
+    for (var property in object) {
+        properties.push(property);
+    }
+    return properties.sort();
+}
+
 function stringify(v)
 {
     if (isNewSVGTearOffType(v))
@@ -199,6 +209,23 @@ 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 = Array.isArray(src) ? [] : {};
+        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")