X64/Win64: Alternative implementation of fmod in general.

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
diff --git a/src/x64/assembler-x64.h b/src/x64/assembler-x64.h
index 7e09a416b562737bc8c75bd912856a0c7799f7ab..856e6b7cb7139506ebf5e47c18ed76fca4b2b384 100644
--- a/src/x64/assembler-x64.h
+++ b/src/x64/assembler-x64.h
@@ -1006,6 +1006,7 @@ class Assembler : public Malloced {
 
   void fstp_s(const Operand& adr);
   void fstp_d(const Operand& adr);
+  void fstp(int index);
 
   void fild_s(const Operand& adr);
   void fild_d(const Operand& adr);
@@ -1056,8 +1057,7 @@ class Assembler : public Malloced {
 
   // SSE2 instructions
   void movsd(const Operand& dst, XMMRegister src);
-  void movsd(Register src, XMMRegister dst);
-  void movsd(XMMRegister dst, Register src);
+  void movsd(XMMRegister src, XMMRegister dst);
   void movsd(XMMRegister src, const Operand& dst);
 
   void cvttss2si(Register dst, const Operand& src);