anchor.diff:  
     ExecutionService(this.frame) {
       window.onMessage.listen((MessageEvent event) {
  -      String message = '${event.data}\n';
  +      String message = '${event.data}';
   
         if (message.startsWith('stderr: ')) {
           _stderrController.add(message.substring(8));
  
positive.code: import 'services/common.dart';
  import 'services/compiler.dart';
  
  // TODO: console output needs to scroll the output field
  
  // TODO: we need blinkers when something happens. console is appended to,
  // css is updated, result area dom is modified.
  
  
negative.code:     // Set up iframe.
      executionService = new ExecutionService(_frame);
      executionService.onStdout.listen(_showOuput);
      executionService.onStderr.listen((m) => _showOuput(m, error: true));
  
      runbutton = new DButton(querySelector('#runbutton'));
      runbutton.onClick.listen((e) {
  