Extract DiagnosticReporter implementation from Compiler.

pkg/compiler/lib/src/js_emitter/startup_emitter/emitter.dart

 // Copyright (c) 2015, 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 dart2js.js_emitter.startup_emitter;
 
 import 'package:js_runtime/shared/embedded_names.dart' show
     JsBuiltin,
     METADATA,
     STATIC_FUNCTION_NAME_TO_CLOSURE,
     TYPES;
 
 import '../program_builder/program_builder.dart' show ProgramBuilder;
 import '../model.dart';
 import 'model_emitter.dart';
 import '../../common.dart';
 import '../../elements/elements.dart' show FieldElement;
 import '../../js/js.dart' as js;
 
 import '../../js_backend/js_backend.dart' show
     JavaScriptBackend,
     Namer;
 
 import '../js_emitter.dart' show
     NativeEmitter;
 
 import '../js_emitter.dart' as emitterTask show
     Emitter;
 
+import '../../diagnostics/diagnostic_listener.dart' show
+    DiagnosticReporter;
+
 import '../../diagnostics/spannable.dart' show
     NO_LOCATION_SPANNABLE;
 
 class Emitter implements emitterTask.Emitter {
   final Compiler _compiler;
   final Namer namer;
   final ModelEmitter _emitter;
 
   JavaScriptBackend get _backend => _compiler.backend;
 
   Emitter(Compiler compiler, Namer namer, NativeEmitter nativeEmitter,
       bool shouldGenerateSourceMap)
       : this._compiler = compiler,
         this.namer = namer,
         _emitter = new ModelEmitter(
             compiler, namer, nativeEmitter, shouldGenerateSourceMap);
 
+  DiagnosticReporter get reporter => _compiler.reporter;
+
   @override
   String get patchVersion => "startup";
 
   @override
   int emitProgram(ProgramBuilder programBuilder) {
     Program program = programBuilder.buildProgram();
     return _emitter.emitProgram(program);
   }
 
   @override
@@ skipping 120 matching lines @@
         String typesAccess =
             _emitter.generateEmbeddedGlobalAccessString(TYPES);
         return js.js.expressionTemplateFor("$typesAccess[#]");
 
       case JsBuiltin.createDartClosureFromNameOfStaticFunction:
         String functionAccess = _emitter.generateEmbeddedGlobalAccessString(
             STATIC_FUNCTION_NAME_TO_CLOSURE);
         return js.js.expressionTemplateFor("$functionAccess(#)");
 
       default:
-        _compiler.internalError(NO_LOCATION_SPANNABLE,
+        reporter.internalError(NO_LOCATION_SPANNABLE,
             "Unhandled Builtin: $builtin");
         return null;
     }
   }
 
   @override
   void invalidateCaches() {
   }
 }