Extract the AST specific part of NoSuchMethodRegistry

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

Index: pkg/compiler/lib/src/js_backend/backend_helpers.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend_helpers.dart b/pkg/compiler/lib/src/js_backend/backend_helpers.dart
index 252e3217619701b8cda437ede0ee3a8fe0c6e727..c3373d8b89c2de3ce4c584b6f09b4aabae0d3d66 100644
--- a/pkg/compiler/lib/src/js_backend/backend_helpers.dart
+++ b/pkg/compiler/lib/src/js_backend/backend_helpers.dart
@@ -745,6 +745,13 @@ class BackendHelpers {
         commonElements.objectClass, Identifiers.noSuchMethod_);
   }
 
+  bool isDefaultNoSuchMethodImplementation(FunctionEntity element) {
+    ClassEntity classElement = element.enclosingClass;
+    return classElement == commonElements.objectClass ||
+        classElement == jsInterceptorClass ||
+        classElement == jsNullClass;
+  }
+
   ClassEntity get constantMapClass =>
       _findHelperClass(JavaScriptMapConstant.DART_CLASS);
   ClassEntity get constantStringMapClass =>