Access BackendUsage through ClosedWorld

pkg/compiler/lib/src/resolution/resolution_strategy.dart

 // Copyright (c) 2017, 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.resolution_strategy;
 
 import '../common.dart';
 import '../common_elements.dart';
 import '../common/backend_api.dart';
 import '../common/names.dart';
@@ skipping 101 matching lines @@
 
   RuntimeTypesNeedBuilder createRuntimeTypesNeedBuilder() {
     return new ResolutionRuntimeTypesNeedBuilderImpl(
         elementEnvironment, _compiler.types);
   }
 
   ResolutionWorldBuilder createResolutionWorldBuilder(
       NativeBasicData nativeBasicData,
       NativeDataBuilder nativeDataBuilder,
       InterceptorDataBuilder interceptorDataBuilder,
+      BackendUsageBuilder backendUsageBuilder,
       SelectorConstraintsStrategy selectorConstraintsStrategy) {
     return new ElementResolutionWorldBuilder(
         _compiler.backend,
         _compiler.resolution,
         nativeBasicData,
         nativeDataBuilder,
         interceptorDataBuilder,
+        backendUsageBuilder,
         selectorConstraintsStrategy);
   }
 
   WorkItemBuilder createResolutionWorkItemBuilder(
       NativeBasicData nativeBasicData,
       NativeDataBuilder nativeDataBuilder,
       ImpactTransformer impactTransformer) {
     return new ResolutionWorkItemBuilder(_compiler.resolution);
   }
 
@@ skipping 524 matching lines @@
   @override
   WorkItem createWorkItem(MemberElement element) {
     assert(invariant(element, element.isDeclaration));
     if (element.isMalformed) return null;
 
     assert(invariant(element, element is AnalyzableElement,
         message: 'Element $element is not analyzable.'));
     return _resolution.createWorkItem(element);
   }
 }