[turbofan] Add the RoundInt32ToFloat32 operator to turbofan.

src/compiler/x87/instruction-selector-x87.cc

Index: src/compiler/x87/instruction-selector-x87.cc
diff --git a/src/compiler/x87/instruction-selector-x87.cc b/src/compiler/x87/instruction-selector-x87.cc
index cff4aafb278d8c3d5de8a82fcf2dea54f5f45035..ea1ee8b839abdd7813947ddef4ac22917acf49ab 100644
--- a/src/compiler/x87/instruction-selector-x87.cc
+++ b/src/compiler/x87/instruction-selector-x87.cc
@@ -655,6 +655,11 @@ void InstructionSelector::VisitChangeFloat32ToFloat64(Node* node) {
 }
 
 
+void InstructionSelector::VisitRoundInt32ToFloat32(Node* node) {
+  UNIMPLEMENTED();
+}
+
+
 void InstructionSelector::VisitChangeInt32ToFloat64(Node* node) {
   X87OperandGenerator g(this);
   Emit(kX87Int32ToFloat64, g.DefineAsFixed(node, stX_0),