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

frog/lib/natives.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.
 
 // Native helpers generated by the compiler
 // TODO(jmesserly): more natives should use this pattern
 
 // Translate a JavaScript exception to a Dart exception
 // TODO(jmesserly): cross browser support. This is Chrome specific.
 _toDartException(e) native @"""
@@ skipping 27 matching lines @@
       }
       break;
     case 'non_object_property_call':
     case 'non_object_property_load':
       return attachStack(new NullPointerException());
       break;
     case 'undefined_method':
       if (e.arguments[0] == 'call' || e.arguments[0] == 'apply') {
         return attachStack(new ObjectNotClosureException());
       } else {
-        // TODO(jmesserly): can this ever happen?
-        // sra: Yes, seen on '$add'.
+        // TODO(jmesserly): fix noSuchMethod on operators so we don't hit this
         return attachStack(new NoSuchMethodException('', e.arguments[0], []));
       }
       break;
   }
 } else if (e instanceof RangeError) {
   if (e.message.indexOf('call stack') >= 0) {
     return attachStack(new StackOverflowException());
   }
 }
 return e;""" {
   // Ensure constructors are generated
   new ObjectNotClosureException();
   new NullPointerException();
   new NoSuchMethodException(null, null, null);
   new StackOverflowException();
 }