Add support for enabling DCHECKs in release mode

src/lithium-allocator.cc

 // Copyright 2012 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"
 
 #include "src/hydrogen.h"
 #include "src/lithium-inl.h"
 #include "src/lithium-allocator-inl.h"
 #include "src/string-stream.h"
@@ skipping 1501 matching lines @@
         AddToInactive(current);
       }
     }
   }
 
   while (!unhandled_live_ranges_.is_empty()) {
     DCHECK(UnhandledIsSorted());
     LiveRange* current = unhandled_live_ranges_.RemoveLast();
     DCHECK(UnhandledIsSorted());
     LifetimePosition position = current->Start();
-#ifdef DEBUG
+#if DCHECK_IS_ON
     allocation_finger_ = position;
 #endif
     TraceAlloc("Processing interval %d start=%d\n",
                current->id(),
                position.Value());
 
     if (current->HasAllocatedSpillOperand()) {
       TraceAlloc("Live range %d already has a spill operand\n", current->id());
       LifetimePosition next_pos = position;
       if (IsGapAt(next_pos.InstructionIndex())) {
@@ skipping 652 matching lines @@
     isolate()->GetHTracer()->TraceLiveRanges(name(), allocator_);
   }
 
 #ifdef DEBUG
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 
 } }  // namespace v8::internal