Some cleanups to Frog to avoid looking up its builtin types too much

frog/element.dart

 // Copyright (c) 2011, 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.
 
 /**
  * Any abstract representation of a dart element.  This includes
  * [Library], [Type] and [Member].
  */
 class Element implements Hashable {
   // TODO(jimhug): Make name final when we can do it for Library.
@@ skipping 18 matching lines @@
 
   /** Should this element be treated as native JS? */
   bool get isNative() => false;
 
   int hashCode() => name.hashCode();
 
   /** Will return a safe name to refer to this element with in JS code. */
   String get jsname() => _jsname;
 
   /** The native name of this element if it has one. */
-  String get nativeName() => null;
+  String get nativeName() => _jsname;
 
   /** Avoid the native name if hidden native. */
   bool get avoidNativeName() => false;
 
   /**
    * [jsname] priority of this element, if two elements conflict.
    * Higher one gets the name.
    */
   int get jsnamePriority() => isNative ? 2 : (library.isCore ? 1 : 0);
 
@@ skipping 75 matching lines @@
         name = typeRef.func.name.name;
       }
       // Totally bogus!
       typeRef.type = library.getOrAddFunctionType(this, name, typeRef.func);
     } else {
       world.internalError('unknown type reference', node.span);
     }
     return node.type;
   }
 }