PPC: [turbofan] Added the RoundInt64ToFloat64 instruction to TurboFan.

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

Index: src/compiler/ppc/instruction-selector-ppc.cc
diff --git a/src/compiler/ppc/instruction-selector-ppc.cc b/src/compiler/ppc/instruction-selector-ppc.cc
index d211a439135c7fe761ded2abb6a13a1e106e61ff..9b04ec9e5f362afce3374240ca5912f09dbd53a6 100644
--- a/src/compiler/ppc/instruction-selector-ppc.cc
+++ b/src/compiler/ppc/instruction-selector-ppc.cc
@@ -917,6 +917,11 @@ void InstructionSelector::VisitTruncateInt64ToInt32(Node* node) {
   // TODO(mbrandy): inspect input to see if nop is appropriate.
   VisitRR(this, kPPC_Int64ToInt32, node);
 }
+
+
+void InstructionSelector::VisitRoundInt64ToFloat64(Node* node) {
+  VisitRR(this, kPPC_Int64ToDouble, node);
+}
 #endif