[turbofan] Add the RoundInt32ToFloat32 operator to turbofan.

src/compiler/machine-operator.h

Index: src/compiler/machine-operator.h
diff --git a/src/compiler/machine-operator.h b/src/compiler/machine-operator.h
index 00fefe3539bc00dce5d37df2ab64621df61fb9c5..45fed83e4f27f74914ddd20839a13c63079adb5b 100644
--- a/src/compiler/machine-operator.h
+++ b/src/compiler/machine-operator.h
@@ -227,6 +227,7 @@ class MachineOperatorBuilder final : public ZoneObject {
   const Operator* TruncateFloat64ToFloat32();
   const Operator* TruncateFloat64ToInt32(TruncationMode);
   const Operator* TruncateInt64ToInt32();
+  const Operator* RoundInt32ToFloat32();
   const Operator* RoundInt64ToFloat32();
   const Operator* RoundInt64ToFloat64();
   const Operator* RoundUint64ToFloat32();