Fix printing of error codes in unit tests.

pkg/analyzer/test/generated/test_support.dart

 // Copyright (c) 2014, 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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.test_support;
 
 import 'dart:collection';
@@ skipping 292 matching lines @@
     // otherwise record message.
     //
     errorsByCode.forEach((ErrorCode code, List<AnalysisError> actualErrors) {
       int actualCount = actualErrors.length;
       if (buffer.length == 0) {
         buffer.write("Expected ");
       } else {
         buffer.write("; ");
       }
       buffer.write("0 errors of type ");
-      buffer.write("${code.runtimeType}.$code");
+      buffer.write(code.uniqueName);
       buffer.write(", found ");
       buffer.write(actualCount);
       buffer.write(" (");
       for (int i = 0; i < actualErrors.length; i++) {
         AnalysisError error = actualErrors[i];
         if (i > 0) {
           buffer.write(", ");
         }
         buffer.write(error.offset);
       }
@@ skipping 314 matching lines @@
   void getContentsToReceiver(Source_ContentReceiver receiver) {
     throw new UnsupportedOperationException();
   }
   Source resolve(String uri) {
     throw new UnsupportedOperationException();
   }
   Uri resolveRelativeUri(Uri uri) {
     return new Uri(scheme: 'file', path: _name).resolveUri(uri);
   }
 }