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 3dc6188997bdead58671bc9982202033e64f5e38..9951c34f1d1adf388dc34ac33df051d01d3d9075 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -2336,6 +2336,9 @@ class FixedArrayBase: public HeapObject {
   // Length is smi tagged when it is stored.
   static const int kLengthOffset = HeapObject::kHeaderSize;
   static const int kHeaderSize = kLengthOffset + kPointerSize;
+
+  // Gives access to raw memory which stores the array's data.
+  inline Object** data_start();
 };
 
 
@@ -2372,9 +2375,6 @@ 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();