[turbofan] Add RoundUint32ToFloat32 operator to Turbofan.

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 a436a548e09d78c1976e3a138c0a7eebbb10f0a6..3b9ba2a0172e41b92fbf648a9e269c2712759e08 100644
--- a/src/ia32/macro-assembler-ia32.h
+++ b/src/ia32/macro-assembler-ia32.h
@@ -341,6 +341,8 @@ class MacroAssembler: public Assembler {
   void Cvtsi2sd(XMMRegister dst, Register src) { Cvtsi2sd(dst, Operand(src)); }
   void Cvtsi2sd(XMMRegister dst, const Operand& src);
 
+  void Cvtui2ss(XMMRegister dst, Register src, Register tmp);
+
   // Support for constant splitting.
   bool IsUnsafeImmediate(const Immediate& x);
   void SafeMove(Register dst, const Immediate& x);