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

src/compiler/js-graph.h

 // Copyright 2014 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_COMPILER_JS_GRAPH_H_
 #define V8_COMPILER_JS_GRAPH_H_
 
 #include "src/compiler/common-node-cache.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
@@ skipping 96 matching lines @@
   }
 
   // Creates a dummy Constant node, used to satisfy calling conventions of
   // stubs and runtime functions that do not require a context.
   Node* NoContextConstant() { return ZeroConstant(); }
 
   // Creates an empty frame states for cases where we know that a function
   // cannot deopt.
   Node* EmptyFrameState();
 
+  // Create a control node that serves as control dependency for dead nodes.
+  Node* DeadControl();
+
   JSOperatorBuilder* javascript() const { return javascript_; }
   CommonOperatorBuilder* common() const { return common_; }
   MachineOperatorBuilder* machine() const { return machine_; }
   Graph* graph() const { return graph_; }
   Zone* zone() const { return graph()->zone(); }
   Isolate* isolate() const { return isolate_; }
   Factory* factory() const { return isolate()->factory(); }
 
   void GetCachedNodes(NodeVector* nodes);
 
  private:
   Isolate* isolate_;
   Graph* graph_;
   CommonOperatorBuilder* common_;
   JSOperatorBuilder* javascript_;
   MachineOperatorBuilder* machine_;
 
   // TODO(titzer): make this into a simple array.
   SetOncePointer<Node> c_entry_stub_constant_;
   SetOncePointer<Node> undefined_constant_;
   SetOncePointer<Node> the_hole_constant_;
   SetOncePointer<Node> true_constant_;
   SetOncePointer<Node> false_constant_;
   SetOncePointer<Node> null_constant_;
   SetOncePointer<Node> zero_constant_;
   SetOncePointer<Node> one_constant_;
   SetOncePointer<Node> nan_constant_;
   SetOncePointer<Node> empty_frame_state_;
+  SetOncePointer<Node> dead_control_;
 
   CommonNodeCache cache_;
 
   Node* ImmovableHeapConstant(Handle<HeapObject> value);
   Node* NumberConstant(double value);
 
   DISALLOW_COPY_AND_ASSIGN(JSGraph);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif