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

src/compiler/graph.cc

 // 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.
 
 #include "src/compiler/graph.h"
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/generic-node-inl.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/node.h"
 #include "src/compiler/node-aux-data-inl.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/node-properties-inl.h"
 #include "src/compiler/opcodes.h"
 #include "src/compiler/operator-properties.h"
 #include "src/compiler/operator-properties-inl.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
-Graph::Graph(Zone* zone) : GenericGraph<Node>(zone), decorators_(zone) {}
+Graph::Graph(Zone* zone)
+    : GenericGraph<Node>(zone), mark_max_(0), decorators_(zone) {}
 
 
 void Graph::Decorate(Node* node) {
   for (ZoneVector<GraphDecorator*>::iterator i = decorators_.begin();
        i != decorators_.end(); ++i) {
     (*i)->Decorate(node);
   }
 }
 
 
 Node* Graph::NewNode(const Operator* op, int input_count, Node** inputs,
                      bool incomplete) {
   DCHECK_LE(op->ValueInputCount(), input_count);
   Node* result = Node::New(this, input_count, inputs, incomplete);
   result->Initialize(op);
   if (!incomplete) {
     Decorate(result);
   }
   return result;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8