Revert "Parts must start with 'part of'" and "Attempt to fix VM build"

dart/lib/compiler/implementation/diagnostic_listener.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.
 
-part of parser;
-
 abstract class DiagnosticListener {
   // TODO(karlklose): replace cancel with better error reporting mechanism.
   void cancel(String reason, {node, token, instruction, element});
   // TODO(karlklose): rename log to something like reportInfo.
   void log(message);
   // TODO(karlklose): add reportWarning and reportError to this interface.
 
   void internalErrorOnElement(Element element, String message);
   void internalError(String message,
                      {Node node, Token token, HInstruction instruction,
                       Element element});
 
   SourceSpan spanFromNode(Node node, [Uri uri]);
 
   void reportMessage(SourceSpan span, Diagnostic message, api.Diagnostic kind);
 }