Better error message for assignment to final local variables

runtime/lib/invocation_mirror_patch.dart

 // 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.
 
 class _InvocationMirror implements Invocation {
   // Constants describing the invocation type.
   // _FIELD cannot be generated by regular invocation mirrors.
   static const int _METHOD = 0;
   static const int _GETTER = 1;
   static const int _SETTER = 2;
   static const int _FIELD = 3;
+  static const int _LOCAL_VAR = 4;
   static const int _TYPE_SHIFT = 0;
-  static const int _TYPE_BITS = 2;
+  static const int _TYPE_BITS = 3;
   static const int _TYPE_MASK = (1 << _TYPE_BITS) - 1;
 
   // These values, except _DYNAMIC and _SUPER, are only used when throwing
   // NoSuchMethodError for compile-time resolution failures.
   static const int _DYNAMIC = 0;
   static const int _SUPER = 1;
   static const int _STATIC = 2;
   static const int _CONSTRUCTOR = 3;
   static const int _TOP_LEVEL = 4;
   static const int _CALL_SHIFT = _TYPE_BITS;
@@ skipping 104 matching lines @@
   static _allocateInvocationMirror(String functionName,
                                    List argumentsDescriptor,
                                    List arguments,
                                    bool isSuperInvocation) {
     return new _InvocationMirror(functionName,
                                  argumentsDescriptor,
                                  arguments,
                                  isSuperInvocation);
   }
 }