Add support for enabling DCHECKs in release mode

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 09ca02854f12282e81d70327209e7c0f52f1c903..65d9d0a43fca09f0dcd30081e29f9bb85cb3d793 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -118,7 +118,7 @@ base::Thread::LocalStorageKey Isolate::per_isolate_thread_data_key_;
 base::LazyMutex Isolate::thread_data_table_mutex_ = LAZY_MUTEX_INITIALIZER;
 Isolate::ThreadDataTable* Isolate::thread_data_table_ = NULL;
 base::Atomic32 Isolate::isolate_counter_ = 0;
-#if DEBUG
+#if DCHECK_IS_ON
 base::Atomic32 Isolate::isolate_key_created_ = 0;
 #endif
 
@@ -160,7 +160,7 @@ void Isolate::InitializeOncePerProcess() {
   base::LockGuard<base::Mutex> lock_guard(thread_data_table_mutex_.Pointer());
   CHECK(thread_data_table_ == NULL);
   isolate_key_ = base::Thread::CreateThreadLocalKey();
-#if DEBUG
+#if DCHECK_IS_ON
   base::NoBarrier_Store(&isolate_key_created_, 1);
 #endif
   thread_id_key_ = base::Thread::CreateThreadLocalKey();
@@ -228,7 +228,7 @@ void Isolate::IterateDeferredHandles(ObjectVisitor* visitor) {
 }
 
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
 bool Isolate::IsDeferredHandle(Object** handle) {
   // Each DeferredHandles instance keeps the handles to one job in the
   // concurrent recompilation queue, containing a list of blocks.  Each block
@@ -2348,7 +2348,7 @@ Object* Isolate::FindCodeObject(Address a) {
 }
 
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
 #define ISOLATE_FIELD_OFFSET(type, name, ignored)                       \
 const intptr_t Isolate::name##_debug_offset_ = OFFSET_OF(Isolate, name##_);
 ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)