[Reland] Implement Custom Element's class side inheritance

LayoutTests/fast/dom/custom/exception-from-constructor.html

Index: LayoutTests/fast/dom/custom/exception-from-constructor.html
diff --git a/LayoutTests/fast/dom/custom/registration-context-delete-during-register-created-retrieval.html b/LayoutTests/fast/dom/custom/exception-from-constructor.html
similarity index 58%
copy from LayoutTests/fast/dom/custom/registration-context-delete-during-register-created-retrieval.html
copy to LayoutTests/fast/dom/custom/exception-from-constructor.html
index 488859fae9f62d83304976652cb1a85cf1c8a522..b75a11c68d099ad9159f9b0405af44e8e4b8829c 100644
--- a/LayoutTests/fast/dom/custom/registration-context-delete-during-register-created-retrieval.html
+++ b/LayoutTests/fast/dom/custom/exception-from-constructor.html
@@ -5,23 +5,20 @@
 <script>
 if (fork()) {
     // The controlling parent frame
-    description('Tests destroying a context during registration at the point when the created callback is retrieved.');
+    description('Tests throwing an exception during registeration of'

[vivekg, 2015/04/21 09:42:49]

nit: registeration => registration. Also this could be a single line statement
itself.

+    + 'constructor');
     jsTestIsAsync = true;
     successfullyParsed = true;
 } else {
-    // The child frame
-
     var proto = Object.create(HTMLElement.prototype, {
-        createdCallback: {
-            get: function () {
-                destroyContext();
-                return function () { }
+        constructor: {
+            configurable: true,
+            get: function () { throw "Exception thrown from getter"; }
             }
-        }
-    });
+        });
 
     try {
-        document.registerElement('x-a', {prototype: proto});
+        var element = document.registerElement('x-a', {prototype: proto});

[vivekg, 2015/04/21 09:42:49]

Can we use shouldThrow('document.registerElement(...)') here?

         log('FAIL expected register to throw an exception');
     } catch (ex) {
         log('PASS caught expected exception "' + ex + '"');