Fix names with '$' to not conflict with operators or internal helpers

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.
   /** The user-visible name of this [Element]. */
   String name;
 
   /** A safe name to use for this [Element] in generated JS code. */
   String _jsname;
 
   /** The lexically/logically enclosing [Element] for lookups. */
   Element _enclosingElement;
 
   Element(this.name, this._enclosingElement) {
-    _jsname = name;
+    _jsname = world.toJsIdentifier(name);
   }
 
   // TODO - walk tree
   Library get library() => null;
 
   /** A source location for messages to the user about this [Element]. */
   SourceSpan get span() => null;
 
   /** Should this element be treated as native JS? */
   bool get isNative() => false;
@@ skipping 88 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;
   }
 }