Access NativeData only through ClosedWorld

pkg/compiler/lib/src/inferrer/inferrer_engine.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.
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../common.dart';
 import '../common/names.dart';
 import '../compiler.dart';
 import '../constants/expressions.dart';
@@ skipping 202 matching lines @@
         data.setCurrentTypeMask(node, mask);
       } else {
         assert(selector == Selectors.moveNext);
         data.setMoveNextTypeMask(node, mask);
       }
     }
   }
 
   bool isNativeMember(Element element) {
     return element is MemberElement &&
-        compiler.backend.nativeData.isNativeMember(element);
+        closedWorld.nativeData.isNativeMember(element);
   }
 
   bool checkIfExposesThis(Element element) {
     element = element.implementation;
     return generativeConstructorsExposingThis.contains(element);
   }
 
   void recordExposesThis(Element element, bool exposesThis) {
     element = element.implementation;
     if (exposesThis) {
@@ skipping 849 matching lines @@
   /**
    * Records that the captured variable [local] is read.
    */
   void recordCapturedLocalRead(Local local) {}
 
   /**
    * Records that the variable [local] is being updated.
    */
   void recordLocalUpdate(Local local, TypeInformation type) {}
 }