[turbofan] Add TraversalState and GraphTraversal and use them in GraphReducer.

src/compiler/graph-reducer.h

Index: src/compiler/graph-reducer.h
diff --git a/src/compiler/graph-reducer.h b/src/compiler/graph-reducer.h
index f07fb2bebf431e816270d9281f29a892145e4d38..09a650cce8fbb015f798465ee1f245ae8623c2f9 100644
--- a/src/compiler/graph-reducer.h
+++ b/src/compiler/graph-reducer.h
@@ -5,17 +5,13 @@
 #ifndef V8_COMPILER_GRAPH_REDUCER_H_
 #define V8_COMPILER_GRAPH_REDUCER_H_
 
+#include "src/compiler/graph.h"
 #include "src/zone-containers.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
-// Forward declarations.
-class Graph;
-class Node;
-
-
 // Represents the result of trying to reduce a node in the graph.
 class Reduction FINAL {
  public:
@@ -80,17 +76,17 @@ class GraphReducer FINAL {
 
   // Node stack operations.
   void Pop();
-  void Push(Node* const);
+  void Push(Node* node);
 
   // Revisit queue operations.
-  bool Recurse(Node* const);
-  void Revisit(Node* const);
+  bool Recurse(Node* node);
+  void Revisit(Node* node);
 
   Graph* graph_;
+  NodeMarker<State> state_;
   ZoneVector<Reducer*> reducers_;
   ZoneStack<Node*> revisit_;
   ZoneStack<NodeState> stack_;
-  ZoneDeque<State> state_;
 
   DISALLOW_COPY_AND_ASSIGN(GraphReducer);
 };