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

pkg/compiler/lib/src/ssa/interceptor_simplifier.dart

 // Copyright (c) 2013, 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.
 
 part of ssa;
 
 /**
  * This phase simplifies interceptors in multiple ways:
  *
  * 1) If the interceptor is for an object whose type is known, it
@@ skipping 149 matching lines @@
       // interceptor directly.
 
       // TODO(sra): Key DOM classes like Node, Element and Event are not leaf
       // classes.  When the receiver type is not a leaf class, we might still be
       // able to use the receiver class as a constant interceptor.  It is
       // usually the case that methods defined on a non-leaf class don't test
       // for a subclass or call methods defined on a subclass.  Provided the
       // code is completely insensitive to the specific instance subclasses, we
       // can use the non-leaf class directly.
       ClassElement element = type.singleClass(classWorld);
-      if (element != null && element.isNative) {
+      if (element != null && backend.isNative(element)) {
         return element;
       }
     }
 
     return null;
   }
 
   HInstruction findDominator(Iterable<HInstruction> instructions) {
     HInstruction result;
     L1: for (HInstruction candidate in instructions) {
@@ skipping 222 matching lines @@
       instruction = new HInvokeDynamicMethod(
           selector, mask, inputs, node.instructionType, true);
     }
 
     HBasicBlock block = node.block;
     block.addAfter(node, instruction);
     block.rewrite(node, instruction);
     return true;
   }
 }