Fix Mac64-debug issue introduced with r21154.

src/x64/lithium-codegen-x64.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 "v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "x64/lithium-codegen-x64.h"
 #include "code-stubs.h"
@@ skipping 1674 matching lines @@
 }
 
 
 void LCodeGen::DoConstantE(LConstantE* instr) {
   __ LoadAddress(ToRegister(instr->result()), instr->value());
 }
 
 
 void LCodeGen::DoConstantT(LConstantT* instr) {
   Handle<Object> object = instr->value(isolate());
+  AllowDeferredHandleDereference smi_check;
   if (instr->hydrogen()->HasObjectMap()) {
     Handle<Map> object_map = instr->hydrogen()->ObjectMap().handle();
     CHECK(object->IsHeapObject());
     CHECK(!object_map->is_stable() ||
           *object_map == Handle<HeapObject>::cast(object)->map());
   }
   __ Move(ToRegister(instr->result()), object);
 }
 
 
@@ skipping 4005 matching lines @@
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64