Consistently order receiver and holder argument in ElementAccessor.

src/elements.h

Index: src/elements.h
diff --git a/src/elements.h b/src/elements.h
index c6d2d4b3bb340a18d3f3da1101859125ebfc7e59..036df5f709459aa81f6cfadbe6553357740c9382 100644
--- a/src/elements.h
+++ b/src/elements.h
@@ -42,17 +42,32 @@ class ElementsAccessor {
 
   virtual const char* name() const { return name_; }
 
-  virtual MaybeObject* Get(FixedArrayBase* backing_store,
-                           uint32_t key,
+  // Returns true if a holder contains an element with the specified key
+  // without iterating up the prototype chain.  The caller can optionally pass
+  // in the backing store to use for the check, which must be compatible with
+  // the ElementsKind of the ElementsAccessor. If backing_store is NULL, the
+  // holder->elements() is used as the backing store.
+  virtual bool HasElement(Object* receiver,
+                          JSObject* holder,
+                          uint32_t key,
+                          FixedArrayBase* backing_store = NULL) = 0;
+
+  // Returns the element with the specified key or undefined if there is no such
+  // element. This method doesn't iterate up the prototype chain.  The caller
+  // can optionally pass in the backing store to use for the check, which must
+  // be compatible with the ElementsKind of the ElementsAccessor. If
+  // backing_store is NULL, the holder->elements() is used as the backing store.
+  virtual MaybeObject* Get(Object* receiver,
                            JSObject* holder,
-                           Object* receiver) = 0;
+                           uint32_t key,
+                           FixedArrayBase* backing_store = NULL) = 0;
 
   // Modifies the length data property as specified for JSArrays and resizes the
   // underlying backing store accordingly. The method honors the semantics of
   // changing array sizes as defined in EcmaScript 5.1 15.4.5.2, i.e. array that
   // have non-deletable elements can only be shrunk to the size of highest
   // element that is non-deletable.
-  virtual MaybeObject* SetLength(JSObject* holder,
+  virtual MaybeObject* SetLength(JSArray* holder,
                                  Object* new_length) = 0;
 
   // Modifies both the length and capacity of a JSArray, resizing the underlying
@@ -65,19 +80,15 @@ class ElementsAccessor {
                                             int capacity,
                                             int length) = 0;
 
+  // Deletes an element in an object, returning a new elements backing store.
   virtual MaybeObject* Delete(JSObject* holder,
                               uint32_t key,
                               JSReceiver::DeleteMode mode) = 0;
 
-  virtual bool HasElement(FixedArrayBase* backing_store,
-                          uint32_t key,
-                          JSObject* holder,
-                          Object* receiver) = 0;
-
-  virtual MaybeObject* AddElementsToFixedArray(FixedArrayBase* from,
-                                               FixedArray* to,
+  virtual MaybeObject* AddElementsToFixedArray(Object* receiver,
                                                JSObject* holder,
-                                               Object* receiver) = 0;
+                                               FixedArray* to,
+                                               FixedArrayBase* from = NULL) = 0;
 
   // Returns a shared ElementsAccessor for the specified ElementsKind.
   static ElementsAccessor* ForKind(ElementsKind elements_kind) {