Move remaining helpers to BackendHelpers

pkg/compiler/lib/src/js_emitter/full_emitter/emitter.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 dart2js.js_emitter.full_emitter;
 
 import 'dart:convert';
 import 'dart:collection' show HashMap;
 
 import 'package:js_runtime/shared/embedded_names.dart' as embeddedNames;
@@ skipping 38 matching lines @@
     VariableElement;
 import '../../hash/sha1.dart' show Hasher;
 import '../../io/code_output.dart';
 import '../../io/line_column_provider.dart' show
     LineColumnCollector,
     LineColumnProvider;
 import '../../io/source_map_builder.dart' show
     SourceMapBuilder;
 import '../../js/js.dart' as jsAst;
 import '../../js/js.dart' show js;
+import '../../js_backend/backend_helpers.dart' show
+    BackendHelpers;
 import '../../js_backend/js_backend.dart' show
     CheckedModeHelper,
     CompoundName,
     ConstantEmitter,
     CustomElementsAnalysis,
     GetterName,
     JavaScriptBackend,
     JavaScriptConstantCompiler,
     Namer,
     RuntimeTypes,
@@ skipping 2056 matching lines @@
     for (Element element in compiler.enqueuer.codegen.newlyEnqueuedElements) {
       if (element.isInstanceMember) {
         cachedClassBuilders.remove(element.enclosingClass);
 
         nativeEmitter.cachedBuilders.remove(element.enclosingClass);
 
       }
     }
   }
 }