| Index: src/elements.h | 
| diff --git a/src/elements.h b/src/elements.h | 
| index ae48d4ef07257ef8504804c01a986842a977ca6b..a2fb0352cab91c576c73e84147d6b763dbeccf7f 100644 | 
| --- a/src/elements.h | 
| +++ b/src/elements.h | 
| @@ -154,6 +154,12 @@ class ElementsAccessor { | 
| virtual uint32_t GetCapacity(JSObject* holder, | 
| FixedArrayBase* backing_store) = 0; | 
|  | 
| +  // Check an Object's own elements for an element (using SameValueZero | 
| +  // semantics) | 
| +  virtual Maybe<bool> IncludesValue(Isolate* isolate, Handle<JSObject> receiver, | 
| +                                    Handle<Object> value, uint32_t start, | 
| +                                    uint32_t length) = 0; | 
| + | 
| protected: | 
| friend class LookupIterator; | 
|  | 
|  |