Create a NullErrorReporter to use when errors don't need to be recorded.

pkg/analyzer/lib/src/generated/engine.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;
 
 import 'dart:collection';
@@ skipping 10514 matching lines @@
   List<AnalysisError> get errors => _errors;
 
   @override
   String get taskDescription => "generate errors and warnings for ${source.fullName}";
 
   @override
   void internalPerform() {
     TimeCounter_TimeCounterHandle timeCounter = PerformanceStatistics.errors.start();
     try {
       RecordingErrorListener errorListener = new RecordingErrorListener();
-      ErrorReporter errorReporter = new ErrorReporter(errorListener, source);
+      ErrorReporter errorReporter = new ErrorReporterImpl(errorListener, source);
       TypeProvider typeProvider = context.typeProvider;
       //
       // Validate the directives
       //
       validateDirectives(context, source, _unit, errorListener);
       //
       // Use the ConstantVerifier to verify the use of constants. This needs to happen before using
       // the ErrorVerifier because some error codes need the computed constant values.
       //
       ConstantVerifier constantVerifier = new ConstantVerifier(errorReporter, libraryElement, typeProvider);
@@ skipping 4032 matching lines @@
     // Resolve the rest of the structure
     //
     InheritanceManager inheritanceManager = new InheritanceManager(_libraryElement);
     ResolverVisitor resolverVisitor = new ResolverVisitor.con2(_libraryElement, source, typeProvider, inheritanceManager, errorListener);
     unit.accept(resolverVisitor);
     //
     // Perform additional error checking.
     //
     TimeCounter_TimeCounterHandle counterHandleErrors = PerformanceStatistics.errors.start();
     try {
-      ErrorReporter errorReporter = new ErrorReporter(errorListener, source);
+      ErrorReporter errorReporter = new ErrorReporterImpl(errorListener, source);
       ErrorVerifier errorVerifier = new ErrorVerifier(errorReporter, _libraryElement, typeProvider, inheritanceManager);
       unit.accept(errorVerifier);
       ConstantVerifier constantVerifier = new ConstantVerifier(errorReporter, _libraryElement, typeProvider);
       unit.accept(constantVerifier);
     } finally {
       counterHandleErrors.stop();
     }
     //
     // Capture the results.
     //
@@ skipping 1041 matching lines @@
     _index++;
     if (_index >= _manager._workQueues[_queueIndex].length) {
       _index = 0;
       _queueIndex++;
       while (_queueIndex < _manager._workQueues.length && _manager._workQueues[_queueIndex].isEmpty) {
         _queueIndex++;
       }
     }
   }
 }