Move DeadControl into the JSGraph so that it can be reused.

src/compiler/control-reducer.cc

Index: src/compiler/control-reducer.cc
diff --git a/src/compiler/control-reducer.cc b/src/compiler/control-reducer.cc
index 9d74b8a6a4fb001f26f581b55c80019631cd0cd4..7f97254b372bf0c4c9a16fbddefd9a0938ca7acd 100644
--- a/src/compiler/control-reducer.cc
+++ b/src/compiler/control-reducer.cc
@@ -54,8 +54,7 @@ class ControlReducerImpl {
         common_(common),
         state_(jsgraph->graph()->NodeCount(), kUnvisited, zone_),
         stack_(zone_),
-        revisit_(zone_),
-        dead_(NULL) {}
+        revisit_(zone_) {}
 
   Zone* zone_;
   JSGraph* jsgraph_;
@@ -63,7 +62,6 @@ class ControlReducerImpl {
   ZoneVector<VisitState> state_;
   ZoneDeque<Node*> stack_;
   ZoneDeque<Node*> revisit_;
-  Node* dead_;
 
   void Reduce() {
     Push(graph()->end());
@@ -380,10 +378,7 @@ class ControlReducerImpl {
     state_[id] = kVisited;
   }
 
-  Node* dead() {
-    if (dead_ == NULL) dead_ = graph()->NewNode(common_->Dead());
-    return dead_;
-  }
+  Node* dead() { return jsgraph_->DeadControl(); }
 
   //===========================================================================
   // Reducer implementation: perform reductions on a node.