[turbofan] Add the RoundInt32ToFloat32 operator to turbofan.

src/x64/assembler-x64.cc

Index: src/x64/assembler-x64.cc
diff --git a/src/x64/assembler-x64.cc b/src/x64/assembler-x64.cc
index 9626efc4a760acaf84176bd0cd77770af790f9ad..3cf3398e876e3a51e291a2e2f60ca88355e8d87b 100644
--- a/src/x64/assembler-x64.cc
+++ b/src/x64/assembler-x64.cc
@@ -3179,6 +3179,17 @@ void Assembler::cvtlsi2sd(XMMRegister dst, Register src) {
 }
 
 
+void Assembler::cvtlsi2ss(XMMRegister dst, const Operand& src) {
+  DCHECK(!IsEnabled(AVX));
+  EnsureSpace ensure_space(this);
+  emit(0xF3);
+  emit_optional_rex_32(dst, src);
+  emit(0x0F);
+  emit(0x2A);
+  emit_sse_operand(dst, src);
+}
+
+
 void Assembler::cvtlsi2ss(XMMRegister dst, Register src) {
   EnsureSpace ensure_space(this);
   emit(0xF3);