Implement UnionOfKeys for NonStrictArguments

src/elements.h

Index: src/elements.h
diff --git a/src/elements.h b/src/elements.h
index 74e4ad665969971843f248e8f5d6a43f9a7b7c8d..9a4afcddc197de28bf2d0a24757ce79c0f5e5dbb 100644
--- a/src/elements.h
+++ b/src/elements.h
@@ -41,10 +41,10 @@ class ElementsAccessor {
   virtual ~ElementsAccessor() { }
   virtual MaybeObject* GetWithReceiver(JSObject* obj,
                                        Object* receiver,
-                                       uint32_t index) = 0;
+                                       uint32_t key) = 0;
 
   virtual MaybeObject* Delete(JSObject* obj,
-                              uint32_t index,
+                              uint32_t key,
                               JSReceiver::DeleteMode mode) = 0;
 
   virtual MaybeObject* AddElementsToFixedArray(FixedArrayBase* from,
@@ -56,8 +56,33 @@ class ElementsAccessor {
     return elements_accessors_[elements_kind];
   }
 
+  static ElementsAccessor* ForArray(FixedArrayBase* array);
+
   static void InitializeOncePerProcess();
 
+ protected:
+  friend class NonStrictArgumentsElementsAccessor;
+
+  // TODO(danno): GetElement should be merged with GetWithReceiver.
+  virtual MaybeObject* GetElement(FixedArrayBase* backing_store,
+                                  uint32_t key) = 0;
+
+  virtual uint32_t GetCapacity(FixedArrayBase* backing_store) = 0;
+
+  virtual bool HasElementAtIndex(FixedArrayBase* backing_store,
+                                 uint32_t index) = 0;
+
+  // Element handlers distinguish between indexes and keys when the manipulate
+  // elements.  Indexes refer to elements in terms of their location in the
+  // underlying storage's backing store representation, and are between 0
+  // GetCapacity.  Keys refer to elements in terms of the value that would be
+  // specific in JavaScript to access the element. In most implementations, keys
+  // are equivalent to indexes, and GetKeyForIndex returns the same value it is
+  // passed. In the NumberDictionary ElementsAccessor, GetKeyForIndex maps the
+  // index to a key using the KeyAt method on the NumberDictionary.
+  virtual uint32_t GetKeyForIndex(FixedArrayBase* backing_store,
+                                  uint32_t index) = 0;
+
  private:
   static ElementsAccessor** elements_accessors_;