[turbofan] Implement rounding of floats on x64 and ia32 without sse4.1.

src/ia32/macro-assembler-ia32.h

Index: src/ia32/macro-assembler-ia32.h
diff --git a/src/ia32/macro-assembler-ia32.h b/src/ia32/macro-assembler-ia32.h
index 282f6dbc0bdcd42f0b6a55752d2185ead9157e6f..1f5ba90fbeb867f6f7e8d3079a6e626d684fe1d9 100644
--- a/src/ia32/macro-assembler-ia32.h
+++ b/src/ia32/macro-assembler-ia32.h
@@ -344,6 +344,13 @@ class MacroAssembler: public Assembler {
   // xorps to clear the dst register before cvtsi2sd to solve this issue.
   void Cvtsi2sd(XMMRegister dst, Register src) { Cvtsi2sd(dst, Operand(src)); }
   void Cvtsi2sd(XMMRegister dst, const Operand& src);
+  void Cvtsi2ss(XMMRegister dst, Register src) { Cvtsi2ss(dst, Operand(src)); }
+  void Cvtsi2ss(XMMRegister dst, const Operand& src);
+
+  void Roundss(XMMRegister dst, XMMRegister src, Register tmp, XMMRegister xtmp,
+               RoundingMode mode);
+  void Roundsd(XMMRegister dst, XMMRegister src, Register tmp, XMMRegister xtmp,
+               RoundingMode mode);
 
   // Support for constant splitting.
   bool IsUnsafeImmediate(const Immediate& x);