pkg/compiler: fix imports

pkg/compiler/lib/src/js_backend/backend_helpers.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_backend.helpers;
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers, Uris;
 import '../common/resolution.dart' show Resolution;
 import '../compiler.dart' show Compiler;
 import '../core_types.dart' show CoreClasses;
 import '../elements/elements.dart'
     show
         AbstractFieldElement,
         ClassElement,
         ConstructorElement,
         Element,
         EnumClassElement,
         FunctionElement,
         LibraryElement,
         MethodElement,
         PublicName;
 import '../library_loader.dart' show LoadedLibraries;
 import '../universe/call_structure.dart' show CallStructure;
 import '../universe/selector.dart' show Selector;
-
 import 'js_backend.dart';
 
 /// Helper classes and functions for the JavaScript backend.
 class BackendHelpers {
   static final Uri DART_JS_HELPER = new Uri(scheme: 'dart', path: '_js_helper');
   static final Uri DART_INTERCEPTORS =
       new Uri(scheme: 'dart', path: '_interceptors');
   static final Uri DART_FOREIGN_HELPER =
       new Uri(scheme: 'dart', path: '_foreign_helper');
   static final Uri DART_JS_MIRRORS =
@@ skipping 669 matching lines @@
   MethodElement _objectNoSuchMethod;
 
   MethodElement get objectNoSuchMethod {
     if (_objectNoSuchMethod == null) {
       _objectNoSuchMethod =
           coreClasses.objectClass.lookupLocalMember(Identifiers.noSuchMethod_);
     }
     return _objectNoSuchMethod;
   }
 }