A64: Use a scope utility to allocate scratch registers.

test/cctest/test-utils-a64.cc

Index: test/cctest/test-utils-a64.cc
diff --git a/test/cctest/test-utils-a64.cc b/test/cctest/test-utils-a64.cc
index e637a6e52b7d1138b300ab3b890c7b04cb126df1..e9aecb825ddd5ac369c7730867930b7be0351b05 100644
--- a/test/cctest/test-utils-a64.cc
+++ b/test/cctest/test-utils-a64.cc
@@ -323,11 +323,8 @@ void RegisterDump::Dump(MacroAssembler* masm) {
   ASSERT(__ StackPointer().Is(csp));
 
   // Ensure that we don't unintentionally clobber any registers.
-  Register old_tmp0 = __ Tmp0();
-  Register old_tmp1 = __ Tmp1();
-  FPRegister old_fptmp0 = __ FPTmp0();
-  __ SetScratchRegisters(NoReg, NoReg);
-  __ SetFPScratchRegister(NoFPReg);
+  UseScratchRegisterScope temps(masm);
+  temps.ExcludeAll();
 
   // Preserve some temporary registers.
   Register dump_base = x0;
@@ -418,9 +415,5 @@ void RegisterDump::Dump(MacroAssembler* masm) {
   __ Ldr(dump2_base, MemOperand(dump2, dump2_base.code() * kXRegSizeInBytes));
   __ Ldr(dump2, MemOperand(dump2, dump2.code() * kXRegSizeInBytes));
 
-  // Restore the MacroAssembler's scratch registers.
-  __ SetScratchRegisters(old_tmp0, old_tmp1);
-  __ SetFPScratchRegister(old_fptmp0);
-
   completed_ = true;
 }