[turbofan] use double temp registers for stack-stack swap on arm64

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 74b4bd96718fb1fbdc2c44cc4927540c64100749..61e69fcf9cbc7f7840667c9fd59f96a1110353c1 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -959,8 +959,8 @@ void CodeGenerator::AssembleSwap(InstructionOperand* source,
     }
   } else if (source->IsStackSlot() || source->IsDoubleStackSlot()) {
     UseScratchRegisterScope scope(masm());
-    CPURegister temp_0 = scope.AcquireX();
-    CPURegister temp_1 = scope.AcquireX();
+    DoubleRegister temp_0 = scope.AcquireD();
+    DoubleRegister temp_1 = scope.AcquireD();
     MemOperand src = g.ToMemOperand(source, masm());
     MemOperand dst = g.ToMemOperand(destination, masm());
     __ Ldr(temp_0, src);