Porting r9605 to x64 (elements kind conversion in generated code).

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 7e0ba00546c167988f97f6daa3411cc075d7c984..526ea7ff1c9fd51f834a3d1aba286ed57ddcfc6b 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -256,8 +256,8 @@ class MacroAssembler: public Assembler {
 
   // Notify the garbage collector that we wrote a pointer into a fixed array.
   // |array| is the array being stored into, |value| is the
-  // object being stored.  |index| is the array index represented as a
-  // Smi. All registers are clobbered by the operation RecordWriteArray
+  // object being stored.  |index| is the array index represented as a non-smi.
+  // All registers are clobbered by the operation RecordWriteArray
   // filters out smis so it does not update the write barrier if the
   // value is a smi.
   void RecordWriteArray(