Access BackendUsage through ClosedWorld

pkg/compiler/lib/src/ssa/graph_builder.dart

 // Copyright (c) 2016, 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.
 
 import '../closure.dart';
 import '../constants/constant_system.dart';
 import '../common/codegen.dart' show CodegenRegistry;
 import '../common_elements.dart';
 import '../compiler.dart';
 import '../deferred_load.dart';
@@ skipping 57 matching lines @@
 
   GlobalTypeInferenceResults get globalInferenceResults =>
       compiler.globalInference.results;
 
   ClosureTask get closureToClassMapper => compiler.closureToClassMapper;
 
   NativeData get nativeData => closedWorld.nativeData;
 
   InterceptorData get interceptorData => closedWorld.interceptorData;
 
-  BackendUsage get backendUsage => backend.backendUsage;
+  BackendUsage get backendUsage => closedWorld.backendUsage;
 
   Namer get namer => backend.namer;
 
   RuntimeTypesNeed get rtiNeed => backend.rtiNeed;
 
   JavaScriptConstantCompiler get constants => backend.constants;
 
   ConstantSystem get constantSystem => constants.constantSystem;
 
   RuntimeTypesEncoder get rtiEncoder => backend.rtiEncoder;
@@ skipping 206 matching lines @@
         return mirrorsData.mustRetainMetadata;
       case 'USE_CONTENT_SECURITY_POLICY':
         return options.useContentSecurityPolicy;
       case 'IS_FULL_EMITTER':
         return !USE_LAZY_EMITTER && !options.useStartupEmitter;
       default:
         return null;
     }
   }
 }