Access NativeData only through ClosedWorld

pkg/compiler/lib/src/js_emitter/native_emitter.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.js_emitter.native_emitter;
 
 import '../common.dart';
 import '../compiler.dart' show Compiler;
 import '../elements/types.dart' show DartType, FunctionType;
 import '../elements/entities.dart';
 import '../js/js.dart' as jsAst;
 import '../js/js.dart' show js;
 import '../js_backend/js_backend.dart' show JavaScriptBackend, Namer;
 import '../js_backend/interceptor_data.dart';
 import '../js_backend/native_data.dart';
 import '../universe/world_builder.dart' show CodegenWorldBuilder;
 
 import 'code_emitter_task.dart' show CodeEmitterTask;
 import 'model.dart';
 
 class NativeEmitter {
   final CodeEmitterTask emitterTask;
+  final NativeData nativeData;
 
   // Whether the application contains native classes.
   bool hasNativeClasses = false;
 
   // Caches the native subtypes of a native class.
   Map<ClassEntity, List<ClassEntity>> subtypes =
       <ClassEntity, List<ClassEntity>>{};
 
   // Caches the direct native subtypes of a native class.
   Map<ClassEntity, List<ClassEntity>> directSubtypes =
       <ClassEntity, List<ClassEntity>>{};
 
   // Caches the methods that have a native body.
   Set<FunctionEntity> nativeMethods = new Set<FunctionEntity>();
 
-  NativeEmitter(CodeEmitterTask emitterTask) : this.emitterTask = emitterTask;
+  NativeEmitter(this.emitterTask, this.nativeData);
 
   Compiler get compiler => emitterTask.compiler;
 
   JavaScriptBackend get backend => compiler.backend;
 
   CodegenWorldBuilder get worldBuilder => compiler.codegenWorldBuilder;
 
-  NativeData get nativeData => backend.nativeData;
-
   InterceptorData get interceptorData => backend.interceptorData;
 
   Namer get namer => backend.namer;
 
   /**
    * Prepares native classes for emission. Returns the unneeded classes.
    *
    * Removes trivial classes (that can be represented by a super type) and
    * generates properties that have to be added to classes (native or not).
    *
@@ skipping 304 matching lines @@
     // satisfy a check against [element], in which case an interceptor must be
     // used.  We should also use an interceptor if the check can't be satisfied
     // by a native class in case we get a native instance that tries to spoof
     // the type info.  i.e the criteria for whether or not to use an interceptor
     // is whether the receiver can be native, not the type of the test.
     ClassEntity cls = element;
     if (nativeData.isNativeOrExtendsNative(cls)) return true;
     return isSupertypeOfNativeClass(element);
   }
 }