[turbofan] Implemented the ChangeFloat64ToInt64 TurboFan operator.

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 47014253f353ffd0c7353b61cbe6beff97124922..e825e3af7ceefeafedadce0fb75dedede2fadd53 100644
--- a/src/compiler/ppc/instruction-selector-ppc.cc
+++ b/src/compiler/ppc/instruction-selector-ppc.cc
@@ -927,6 +927,11 @@ void InstructionSelector::VisitChangeFloat64ToUint32(Node* node) {
 
 
 #if V8_TARGET_ARCH_PPC64
+void InstructionSelector::VisitChangeFloat64ToInt64(Node* node) {
+  VisitRR(this, kPPC_DoubleToInt64, node);
+}
+
+
 void InstructionSelector::VisitChangeInt32ToInt64(Node* node) {
   // TODO(mbrandy): inspect input to see if nop is appropriate.
   VisitRR(this, kPPC_ExtendSignWord32, node);