[turbofan] Implemented the ChangeFloat64ToInt64 TurboFan operator.

src/compiler/arm64/code-generator-arm64.cc

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index 748d94c159f6b978caef2a35e40d26fb4bda257c..60c0e024cd60d9535d7365d7944e17c34b0694e2 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -980,6 +980,9 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kArm64Float64ToUint32:
       __ Fcvtzu(i.OutputRegister32(), i.InputDoubleRegister(0));
       break;
+    case kArm64Float64ToInt64:
+      __ Fcvtzs(i.OutputRegister64(), i.InputDoubleRegister(0));
+      break;
     case kArm64Int32ToFloat64:
       __ Scvtf(i.OutputDoubleRegister(), i.InputRegister32(0));
       break;