Add support for enabling DCHECKs in release mode

src/hydrogen-flow-engine.h

Index: src/hydrogen-flow-engine.h
diff --git a/src/hydrogen-flow-engine.h b/src/hydrogen-flow-engine.h
index 257ab466a1ec4f514a9000f7aa40600221269466..15c277b58894671c0a8b4c77f457667ee696de4d 100644
--- a/src/hydrogen-flow-engine.h
+++ b/src/hydrogen-flow-engine.h
@@ -68,13 +68,13 @@ template <class State, class Effects>
 class HFlowEngine {
  public:
   HFlowEngine(HGraph* graph, Zone* zone)
-    : graph_(graph),
-      zone_(zone),
-#if DEBUG
-      pred_counts_(graph->blocks()->length(), zone),
+      : graph_(graph),
+        zone_(zone),
+#if DCHECK_IS_ON
+        pred_counts_(graph->blocks()->length(), zone),
 #endif
-      block_states_(graph->blocks()->length(), zone),
-      loop_effects_(graph->blocks()->length(), zone) {
+        block_states_(graph->blocks()->length(), zone),
+        loop_effects_(graph->blocks()->length(), zone) {
     loop_effects_.AddBlock(NULL, graph_->blocks()->length(), zone);
   }
 
@@ -186,7 +186,7 @@ class HFlowEngine {
   }
 
   inline void InitializeStates() {
-#if DEBUG
+#if DCHECK_IS_ON
     pred_counts_.Rewind(0);
     pred_counts_.AddBlock(0, graph_->blocks()->length(), zone_);
 #endif
@@ -199,14 +199,14 @@ class HFlowEngine {
   }
 
   inline void IncrementPredecessorCount(HBasicBlock* block) {
-#if DEBUG
+#if DCHECK_IS_ON
     pred_counts_[block->block_id()]++;
 #endif
   }
 
   HGraph* graph_;                    // The hydrogen graph.
   Zone* zone_;                       // Temporary zone.
-#if DEBUG
+#if DCHECK_IS_ON
   ZoneList<int> pred_counts_;        // Finished predecessors (by block id).
 #endif
   ZoneList<State*> block_states_;    // Block states (by block id).