Extract DiagnosticReporter implementation from Compiler.

pkg/compiler/lib/src/js/js.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 js;
 
 import 'package:js_ast/js_ast.dart';
 export 'package:js_ast/js_ast.dart';
 
 import '../compiler.dart' show
     Compiler;
+import '../diagnostics/diagnostic_listener.dart' show
+    DiagnosticReporter;
 import '../diagnostics/spannable.dart' show
     NO_LOCATION_SPANNABLE;
 import '../dump_info.dart' show
     DumpInfoTask;
 import '../io/code_output.dart' show
     CodeBuffer,
     CodeOutput;
 import '../js_emitter/js_emitter.dart' show
     USE_LAZY_EMITTER;
 
@@ skipping 11 matching lines @@
       shouldCompressOutput: compiler.enableMinification,
       minifyLocalVariables: allowVariableMinification,
       preferSemicolonToNewlineInMinifiedOutput: USE_LAZY_EMITTER,
       renamerForNames: renamerForNames);
   CodeBuffer outBuffer = new CodeBuffer();
   SourceInformationProcessor sourceInformationProcessor =
       sourceInformationFactory.createProcessor(
           new SourceLocationsMapper(outBuffer));
   Dart2JSJavaScriptPrintingContext context =
       new Dart2JSJavaScriptPrintingContext(
-          compiler, monitor, outBuffer, sourceInformationProcessor);
+          compiler.reporter, monitor, outBuffer, sourceInformationProcessor);
   Printer printer = new Printer(options, context);
   printer.visit(node);
   sourceInformationProcessor.process(node);
   return outBuffer;
 }
 
 class Dart2JSJavaScriptPrintingContext implements JavaScriptPrintingContext {
-  final Compiler compiler;
+  final DiagnosticReporter reporter;
   final DumpInfoTask monitor;
   final CodeBuffer outBuffer;
   final CodePositionListener codePositionListener;
 
   Dart2JSJavaScriptPrintingContext(
-      this.compiler,
+      this.reporter,
       this.monitor,
       this.outBuffer,
       this.codePositionListener);
 
   @override
   void error(String message) {
-    compiler.internalError(NO_LOCATION_SPANNABLE, message);
+    reporter.internalError(NO_LOCATION_SPANNABLE, message);
   }
 
   @override
   void emit(String string) {
     outBuffer.add(string);
   }
 
   @override
   void enterNode(Node, int startPosition) {}
 
@@ skipping 82 matching lines @@
         }
       }
       _cachedLiteral = js.escapedString(text);
     }
     return _cachedLiteral;
   }
 
   @override
   String get value => _literal.value;
 }