x64: Add MulI and DivI to lithium instructions.

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
===================================================================
--- src/x64/assembler-x64.h	(revision 6669)
+++ src/x64/assembler-x64.h	(working copy)
@@ -865,6 +865,7 @@
   void imul(Register dst, Register src, Immediate imm);  // dst = src * imm.
   // Signed 32-bit multiply instructions.
   void imull(Register dst, Register src);                 // dst = dst * src.
+  void imull(Register dst, const Operand& src);           // dst = dst * src.
   void imull(Register dst, Register src, Immediate imm);  // dst = src * imm.
 
   void incq(Register dst);