Access NativeData only through ClosedWorld

pkg/compiler/lib/src/js_backend/namer.dart

Index: pkg/compiler/lib/src/js_backend/namer.dart
diff --git a/pkg/compiler/lib/src/js_backend/namer.dart b/pkg/compiler/lib/src/js_backend/namer.dart
index 784a9405af9e2179f1d422f8435df81b0c35e494..914ca6325661525d7c14f97e166254919bce32d5 100644
--- a/pkg/compiler/lib/src/js_backend/namer.dart
+++ b/pkg/compiler/lib/src/js_backend/namer.dart
@@ -489,7 +489,6 @@ class Namer {
   static final RegExp IDENTIFIER = new RegExp(r'^[A-Za-z_$][A-Za-z0-9_$]*$');
   static final RegExp NON_IDENTIFIER_CHAR = new RegExp(r'[^A-Za-z_0-9$]');
 
-  final NativeData _nativeData;
   final ClosedWorld _closedWorld;
   final CodegenWorldBuilder _codegenWorldBuilder;
 
@@ -561,7 +560,7 @@ class Namer {
   final Map<LibraryElement, String> _libraryKeys =
       new HashMap<LibraryElement, String>();
 
-  Namer(this._nativeData, this._closedWorld, this._codegenWorldBuilder) {
+  Namer(this._closedWorld, this._codegenWorldBuilder) {
     _literalAsyncPrefix = new StringBackedName(asyncPrefix);
     _literalGetterPrefix = new StringBackedName(getterPrefix);
     _literalSetterPrefix = new StringBackedName(setterPrefix);
@@ -570,6 +569,8 @@ class Namer {
 
   CommonElements get _commonElements => _closedWorld.commonElements;
 
+  NativeData get _nativeData => _closedWorld.nativeData;
+
   String get deferredTypesName => 'deferredTypes';
   String get isolateName => 'Isolate';
   String get isolatePropertiesName => r'$isolateProperties';