Extract DiagnosticReporter implementation from Compiler.

tests/compiler/dart2js/backend_dart/dart_printer_test.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.
 
 library dart_printer_test;
 
 import 'dart:mirrors';
 import 'package:expect/expect.dart';
 import 'package:compiler/src/constants/values.dart';
 import 'package:compiler/src/dart_backend/backend_ast_nodes.dart';
@@ skipping 33 matching lines @@
           buf.write(', ');
         unparse(y);
       }
       buf.write(']');
     }
   }
   unparse(x);
   print("${x.runtimeType}: ${buf.toString()}");
 }
 
-class PrintDiagnosticListener implements DiagnosticListener {
+class PrintDiagnosticListener implements DiagnosticReporter {
   void log(message) {
     print(message);
   }
 
   void internalError(Spannable spannable, message) {
     print(message);
   }
 
   SourceSpan spanFromSpannable(Spannable node) {
     return new SourceSpan(null, 0, 0);
@@ skipping 914 matching lines @@
   checkStatement("do while(x); while (y);");
   checkStatement("{do; while(x); while (y);}");
 
   checkStatement('switch(x) { case 1: case 2: return y; }');
   checkStatement('switch(x) { default: return y; }');
   checkStatement('switch(x) { case 1: x=y; default: return y; }');
   checkStatement('switch(x) { case 1: x=y; y=z; break; default: return y; }');
 
 }