[turbofan] Add the RoundInt32ToFloat32 operator to turbofan.

src/compiler/x64/instruction-selector-x64.cc

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index c47a42eefe3da6684257f8cbfa9bdc6f3c2a661d..f4af583e5e35e9270b08976d9486789f39a8d4d0 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -1046,6 +1046,12 @@ void InstructionSelector::VisitTruncateInt64ToInt32(Node* node) {
 }
 
 
+void InstructionSelector::VisitRoundInt32ToFloat32(Node* node) {
+  X64OperandGenerator g(this);
+  Emit(kSSEInt32ToFloat32, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
+}
+
+
 void InstructionSelector::VisitRoundInt64ToFloat32(Node* node) {
   X64OperandGenerator g(this);
   Emit(kSSEInt64ToFloat32, g.DefineAsRegister(node), g.Use(node->InputAt(0)));