Move native and js interop properties from the element model to the JS backend

pkg/compiler/lib/src/resolution/resolution.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.resolution;
 
 import 'dart:collection' show Queue;
 
 import '../common.dart';
 import '../common/names.dart' show
@@ skipping 174 matching lines @@
       case AsyncMarker.SYNC_STAR:
         compiler.iterableClass.ensureResolved(resolution);
         break;
       }
     }
   }
 
   bool _isNativeClassOrExtendsNativeClass(ClassElement classElement) {
     assert(classElement != null);
     while (classElement != null) {
-      if (classElement.isNative) return true;
+      if (compiler.backend.isNative(classElement)) return true;
       classElement = classElement.superclass;
     }
     return false;
   }
 
   WorldImpact resolveMethodElementImplementation(
       FunctionElement element, FunctionExpression tree) {
     return reporter.withCurrentElement(element, () {
       if (element.isExternal && tree.hasBody()) {
         reporter.reportErrorMessage(
@@ skipping 870 matching lines @@
   TreeElements get treeElements {
     assert(invariant(this, _treeElements !=null,
         message: "TreeElements have not been computed for $this."));
     return _treeElements;
   }
 
   void reuseElement() {
     _treeElements = null;
   }
 }