X87: [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 a7a826d10b199ce053a891e6641d1e2222b053fc..60d4c20b1136901039f13ba31f3ec028e6326319 100644
--- a/src/compiler/x87/instruction-selector-x87.cc
+++ b/src/compiler/x87/instruction-selector-x87.cc
@@ -656,7 +656,9 @@ void InstructionSelector::VisitChangeFloat32ToFloat64(Node* node) {
 
 
 void InstructionSelector::VisitRoundInt32ToFloat32(Node* node) {
-  UNIMPLEMENTED();
+  X87OperandGenerator g(this);
+  Emit(kX87Int32ToFloat32, g.DefineAsFixed(node, stX_0),
+       g.Use(node->InputAt(0)));
 }