Extract InterceptorData from JavaScriptBackend.

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

 // Copyright (c) 2016, 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 js_backend.native_data;
 
 import '../common.dart';
 import '../elements/elements.dart'
     show ClassElement, Element, FieldElement, FunctionElement, MemberElement;
 import '../elements/entities.dart';
@@ skipping 113 matching lines @@
   /// JavaScriptInterop mechanism which is allowed for user libraries.
   bool isNative(Element element) {
     if (isJsInterop(element)) return true;
     if (element.isClass) {
       return nativeClassTagInfo.containsKey(element.declaration);
     } else {
       return nativeMemberName.containsKey(element.declaration);
     }
   }
 
+  /// Returns `true` if [element] or any of its superclasses is native.
+  bool isNativeOrExtendsNative(ClassElement element) {
+    if (element == null) return false;
+    if (isNative(element) || isJsInterop(element)) {
+      return true;
+    }
+    assert(element.isResolved);
+    return isNativeOrExtendsNative(element.superclass);
+  }
+
   /// Sets the native [name] for the member [element]. This name is used for
   /// [element] in the generated JavaScript.
   void setNativeMemberName(MemberElement element, String name) {
     // TODO(johnniwinther): Avoid setting this more than once. The enqueuer
     // might enqueue [element] several times (before processing it) and computes
     // name on each call to `internalAddToWorkList`.
     assert(invariant(
         element,
         nativeMemberName[element.declaration] == null ||
             nativeMemberName[element.declaration] == name,
@@ skipping 82 matching lines @@
   }
 
   /// Apply JS$ escaping scheme to convert possible escaped Dart names into
   /// JS names.
   String getUnescapedJSInteropName(String name) {
     return name.startsWith(_jsInteropEscapePrefix)
         ? name.substring(_jsInteropEscapePrefix.length)
         : name;
   }
 }