Add support for enabling DCHECKs in release mode

src/arm64/codegen-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/arm64/simulator-arm64.h"
 #include "src/codegen.h"
@@ skipping 370 matching lines @@
 
 #ifdef DEBUG
   const int length = kCodeAgeStubEntryOffset / kInstructionSize;
   DCHECK(old_sequence_.length() >= kCodeAgeStubEntryOffset);
   PatchingAssembler patcher_old(old_sequence_.start(), length);
   MacroAssembler::EmitCodeAgeSequence(&patcher_old, NULL);
 #endif
 }
 
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
 bool CodeAgingHelper::IsOld(byte* candidate) const {
   return memcmp(candidate, old_sequence_.start(), kCodeAgeStubEntryOffset) == 0;
 }
 #endif
 
 
 bool Code::IsYoungSequence(Isolate* isolate, byte* sequence) {
   return MacroAssembler::IsYoungSequence(isolate, sequence);
 }
 
@@ skipping 228 matching lines @@
   __ Fmul(result, double_temp3, double_temp1);
 
   __ Bind(&done);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64