Fixing up Table.createTBody et al.

lib/html/templates/html/dart2js/impl_TableElement.darttemplate

Index: lib/html/templates/html/dart2js/impl_TableElement.darttemplate
diff --git a/lib/html/templates/html/dart2js/impl_IFrameElement.darttemplate b/lib/html/templates/html/dart2js/impl_TableElement.darttemplate
similarity index 52%
copy from lib/html/templates/html/dart2js/impl_IFrameElement.darttemplate
copy to lib/html/templates/html/dart2js/impl_TableElement.darttemplate
index 5f91ec8526b603ca0f668c5b44fca66afe7f3161..5a9a49b8c67cc95c3fa42e9a64c2ac14e2b39838 100644
--- a/lib/html/templates/html/dart2js/impl_IFrameElement.darttemplate
+++ b/lib/html/templates/html/dart2js/impl_TableElement.darttemplate
@@ -5,10 +5,14 @@
 class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 $!MEMBERS
 
-  Window get _contentWindow() native "return this.contentWindow;";
-
-  // Override contentWindow to return secure wrapper.
-  Window get contentWindow {
-    return _DOMWindowCrossFrameImpl._createSafe(_contentWindow);
+  _ElementImpl createTBody() {
+    if (JS('bool', '!!#.createTBody', this)) {
+      return this._createTBody();
+    }
+    var tbody = new Element.tag('tbody');
+    this.elements.add(tbody);
+    return tbody;
   }
+
+  _ElementImpl _createTBody() native 'createTBody';
 }