Turn compile time errors related to missing getters and setters into invocation

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 InvocationMirror {
   // Constants describing the invocation type.
   static final int _METHOD = 0;
   static final int _GETTER = 1;
   static final int _SETTER = 2;
 
@@ skipping 90 matching lines @@
     return new _InvocationMirror(functionName, argumentsDescriptor, arguments);
   }
 
   static _invoke(Object receiver,
                  String functionName,
                  List argumentsDescriptor,
                  List arguments)
       native "InvocationMirror_invoke";
 
   invokeOn(Object receiver) {
-    _invoke(receiver, _functionName, _argumentsDescriptor, _arguments);
+    return _invoke(receiver, _functionName, _argumentsDescriptor, _arguments);
   }
 }