Add support for enabling DCHECKs in release mode

src/hydrogen-environment-liveness.h

 // 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.
 
 #ifndef V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_
 #define V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_
 
 
 #include "src/hydrogen.h"
 
@@ skipping 14 matching lines @@
   explicit HEnvironmentLivenessAnalysisPhase(HGraph* graph);
 
   void Run();
 
  private:
   void ZapEnvironmentSlot(int index, HSimulate* simulate);
   void ZapEnvironmentSlotsInSuccessors(HBasicBlock* block, BitVector* live);
   void ZapEnvironmentSlotsForInstruction(HEnvironmentMarker* marker);
   void UpdateLivenessAtBlockEnd(HBasicBlock* block, BitVector* live);
   void UpdateLivenessAtInstruction(HInstruction* instr, BitVector* live);
-#ifdef DEBUG
+#if DCHECK_IS_ON
   bool VerifyClosures(Handle<JSFunction> a, Handle<JSFunction> b);
 #endif
 
   int block_count_;
 
   // Largest number of local variables in any environment in the graph
   // (including inlined environments).
   int maximum_environment_size_;
 
   // Per-block data. All these lists are indexed by block_id.
@@ skipping 13 matching lines @@
   HSimulate* last_simulate_;
   BitVector went_live_since_last_simulate_;
 
   DISALLOW_COPY_AND_ASSIGN(HEnvironmentLivenessAnalysisPhase);
 };
 
 
 } }  // namespace v8::internal
 
 #endif /* V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_ */