Move remaining helpers to BackendHelpers

pkg/compiler/lib/src/compiler.dart

 // Copyright (c) 2012, 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.compiler_base;
 
 import 'dart:async' show
     EventSink,
     Future;
 
@@ skipping 55 matching lines @@
     LibraryElementX,
     PrefixElementX;
 import 'enqueue.dart' show
     CodegenEnqueuer,
     Enqueuer,
     EnqueueTask,
     ResolutionEnqueuer,
     QueueFilter;
 import 'io/source_information.dart' show
     SourceInformation;
+import 'js_backend/backend_helpers.dart' as js_backend show
+    BackendHelpers;
 import 'js_backend/js_backend.dart' as js_backend show
     JavaScriptBackend;
 import 'library_loader.dart' show
     LibraryLoader,
     LibraryLoaderTask,
     LoadedLibraries;
 import 'mirrors_used.dart' show
     MirrorUsageAnalyzerTask;
 import 'null_compiler_output.dart' show
     NullCompilerOutput,
@@ skipping 503 matching lines @@
     } else if (uri == Uris.dart_mirrors) {
       mirrorSystemClass = findRequiredElement(library, 'MirrorSystem');
       mirrorsUsedClass = findRequiredElement(library, 'MirrorsUsed');
     } else if (uri == Uris.dart_async) {
       asyncLibrary = library;
       deferredLibraryClass = findRequiredElement(library, 'DeferredLibrary');
       _coreTypes.futureClass = findRequiredElement(library, 'Future');
       _coreTypes.streamClass = findRequiredElement(library, 'Stream');
     } else if (uri == Uris.dart__native_typed_data) {
       typedDataClass = findRequiredElement(library, 'NativeTypedData');
-    } else if (uri == js_backend.JavaScriptBackend.DART_JS_HELPER) {
+    } else if (uri == js_backend.BackendHelpers.DART_JS_HELPER) {
       patchAnnotationClass = findRequiredElement(library, '_Patch');
       nativeAnnotationClass = findRequiredElement(library, 'Native');
     }
     return backend.onLibraryScanned(library, loader);
   }
 
   /// Compute the set of distinct import chains to the library at [uri] within
   /// [loadedLibraries].
   ///
   /// The chains are strings of the form
@@ skipping 1429 matching lines @@
     if (_otherDependencies == null) {
       _otherDependencies = new Setlet<Element>();
     }
     _otherDependencies.add(element.implementation);
   }
 
   Iterable<Element> get otherDependencies {
     return _otherDependencies != null ? _otherDependencies : const <Element>[];
   }
 }