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

tools/dom/templates/html/impl/impl_Blob.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;
 
 $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
 $!MEMBERS
 $if DART2JS
   factory Blob(List blobParts, [String type, String endings]) {
@@ skipping 13 matching lines @@
   static _create_2(parts, bag) => JS('Blob', 'new Blob(#, #)', parts, bag);
 
   static _create_bag() => JS('var', '{}');
   static _bag_set(bag, key, value) { JS('void', '#[#] = #', bag, key, value); }
 $else
   $if JSINTEROP
   factory Blob(List blobParts, [String type, String endings]) {
     // TODO: any coercions on the elements of blobParts, e.g. coerce a typed
     // array to ArrayBuffer if it is a total view.
 
-    var parts = convertDartToNative_List(blobParts.map(unwrap_jso).toList());
+    var parts = convertDartToNative_List(blobParts);
     if (type == null && endings == null) {
-      return wrap_jso(_blink.BlinkBlob.instance.constructorCallback_1_(parts));
+      return _blink.BlinkBlob.instance.constructorCallback_1_(parts);
     }
     var bag = {};
     if (type != null) bag['type'] = type;
     if (endings != null) bag['endings'] = endings;
-    return wrap_jso(_blink.BlinkBlob.instance.constructorCallback_2_(parts,
-        convertDartToNative_Dictionary(bag)));
+    return _blink.BlinkBlob.instance.constructorCallback_2_(parts,
+        convertDartToNative_Dictionary(bag));
   }
   $endif
 $endif
 }