[turbofan] Add the RoundInt32ToFloat32 operator to turbofan.

src/compiler/mips64/instruction-selector-mips64.cc

Index: src/compiler/mips64/instruction-selector-mips64.cc
diff --git a/src/compiler/mips64/instruction-selector-mips64.cc b/src/compiler/mips64/instruction-selector-mips64.cc
index 1b12bd9aec745fef5fd65f9b7c498f5c64e6b115..f454f18f4a9947a8f7a2f4584353af30a04a7097 100644
--- a/src/compiler/mips64/instruction-selector-mips64.cc
+++ b/src/compiler/mips64/instruction-selector-mips64.cc
@@ -802,6 +802,11 @@ void InstructionSelector::VisitChangeFloat32ToFloat64(Node* node) {
 }
 
 
+void InstructionSelector::VisitRoundInt32ToFloat32(Node* node) {
+  VisitRR(this, kMips64CvtSW, node);
+}
+
+
 void InstructionSelector::VisitChangeInt32ToFloat64(Node* node) {
   VisitRR(this, kMips64CvtDW, node);
 }