Don't dump a stack trace on the user if the formatter had bad output.

lib/src/error_listener.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_style.src.error_listener;
 
 import 'package:analyzer/analyzer.dart';
 
-import 'formatter_exception.dart';
+import 'exceptions.dart';
 
 /// A simple [AnalysisErrorListener] that just collects the reported errors.
 class ErrorListener implements AnalysisErrorListener {
   final _errors = <AnalysisError>[];
 
   void onError(AnalysisError error) {
     _errors.add(error);
   }
 
   /// Throws a [FormatterException] if any errors have been reported.
   void throwIfErrors() {
     if (_errors.isEmpty) return;
 
     throw new FormatterException(_errors);
   }
 }