Speed up ArrayBuffer/typed array/DataView properties.

src/accessors.h

Index: src/accessors.h
diff --git a/src/accessors.h b/src/accessors.h
index d9a2130f6183ce451efed107bcebe2e6a356d9b6..b2dee27932a45f0db0aa42e5de07a0a2cf32b17d 100644
--- a/src/accessors.h
+++ b/src/accessors.h
@@ -86,6 +86,13 @@ class Accessors : public AllStatic {
   static Handle<AccessorInfo> MakeModuleExport(
       Handle<String> name, int index, PropertyAttributes attributes);
 
+  // Returns true for properties that are accessors to object fields.
+  // If true, *object_offset contains offset of object field.
+  static bool IsJSObjectFieldAccessor(
+      Handle<Map> map, Handle<String> name,
+      int* object_offset);
+
+
  private:
   // Accessor functions only used through the descriptor.
   static MaybeObject* FunctionSetPrototype(Isolate* isolate,