Extract DiagnosticReporter implementation from Compiler.

pkg/compiler/lib/src/native/native.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.
 
 library native;
 
 import 'dart:collection' show Queue;
 
 import '../common/backend_api.dart' show
     ForeignResolver;
 import '../common/registry.dart' show
     Registry;
 import '../common/resolution.dart' show
     Parsing,
     Resolution;
 import '../compiler.dart' show
     Compiler;
 import '../constants/values.dart';
+import '../core_types.dart' show
+    CoreTypes;
 import '../dart_types.dart';
-import '../diagnostics/diagnostic_listener.dart';
+import '../diagnostics/diagnostic_listener.dart' show
+    DiagnosticReporter;
 import '../diagnostics/messages.dart' show
     MessageKind;
 import '../diagnostics/spannable.dart' show
     NO_LOCATION_SPANNABLE,
     Spannable;
 import '../enqueue.dart' show
     Enqueuer,
     ResolutionEnqueuer;
 import '../elements/elements.dart';
 import '../elements/modelx.dart' show
@@ skipping 57 matching lines @@
   String quotedName = cls.nativeTagInfo;
   return quotedName.substring(1, quotedName.length - 1).split(',');
 }
 
 List<String> nativeTagsOfClass(ClassElement cls) {
   return nativeTagsOfClassRaw(cls).where((s) => !s.startsWith('!')).toList();
 }
 
 bool nativeTagsForcedNonLeaf(ClassElement cls) =>
     nativeTagsOfClassRaw(cls).contains('!nonleaf');