Support all fast elements kinds in the major array operations.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index d070ecfc289dd31843777eb69e981edd9c82f7c4..fcb850b64b957d08de8d6da2afd55427d36f1d26 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1574,6 +1574,8 @@ class JSObject: public JSReceiver {
   // Returns true if an object has elements of FAST_ELEMENTS or
   // FAST_SMI_ONLY_ELEMENTS.
   inline bool HasFastSmiOrObjectElements();
+  // Returns true if an object has any of the fast elements kinds.
+  inline bool HasFastElements();
   // Returns true if an object has elements of FAST_DOUBLE_ELEMENTS
   // ElementsKind.
   inline bool HasFastDoubleElements();
@@ -2384,12 +2386,12 @@ class FixedArray: public FixedArrayBase {
   inline void set_unchecked(Heap* heap, int index, Object* value,
                             WriteBarrierMode mode);
 
-  // Gives access to raw memory which stores the array's data.
-  inline Object** data_start();
-
   inline Object** GetFirstElementAddress();
   inline bool ContainsOnlySmisOrHoles();
 
+  // Gives access to raw memory which stores the array's data.
+  inline Object** data_start();
+
   // Copy operations.
   MUST_USE_RESULT inline MaybeObject* Copy();
   MUST_USE_RESULT MaybeObject* CopySize(int new_length);
@@ -2491,6 +2493,9 @@ class FixedDoubleArray: public FixedArrayBase {
     return kHeaderSize + length * kDoubleSize;
   }
 
+  // Gives access to raw memory which stores the array's data.
+  inline double* data_start();
+
   // Code Generation support.
   static int OffsetOfElementAt(int index) { return SizeFor(index); }