Optimize dartium dart:html bindings so real world application performance is acceptable. Improves d…

tools/dom/templates/html/impl/impl_HTMLAudioElement.darttemplate

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of $LIBRARYNAME;
 
 @DocsEditable()
 $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
 $!MEMBERS
 $if JSINTEROP
   factory AudioElement([String src]) {
     if (src == null)
-      return wrap_jso(_blink.BlinkHTMLAudioElement.instance.constructorCallback_0_());
+      return _blink.BlinkHTMLAudioElement.instance.constructorCallback_0_();
     else
-      return wrap_jso(_blink.BlinkHTMLAudioElement.instance.constructorCallback_1_(src));
+      return _blink.BlinkHTMLAudioElement.instance.constructorCallback_1_(src);
   }
 $else
   factory AudioElement([String src]) => new AudioElement._(src);
 $endif
 }