Fix build because of dead fields.

src/compiler/graph-visualizer.cc

Index: src/compiler/graph-visualizer.cc
diff --git a/src/compiler/graph-visualizer.cc b/src/compiler/graph-visualizer.cc
index 707a695b0d40585dd834528af60e3f1e46f90f1d..559da32ef4de97c702121d6523c4275186a5dd12 100644
--- a/src/compiler/graph-visualizer.cc
+++ b/src/compiler/graph-visualizer.cc
@@ -219,7 +219,8 @@ std::ostream& operator<<(std::ostream& os, const AsJSON& ad) {
 
 class GraphVisualizer {
  public:
-  GraphVisualizer(std::ostream& os, Zone* zone, const Graph* graph);  // NOLINT
+  GraphVisualizer(std::ostream& os, Zone* zone, const Graph* graph)
+      : all_(zone, graph), os_(os) {}
 
   void Print();
 
@@ -228,10 +229,8 @@ class GraphVisualizer {
  private:
   void PrintEdge(Node::Edge edge);
 
-  Zone* zone_;
   AllNodes all_;
   std::ostream& os_;
-  const Graph* const graph_;
 
   DISALLOW_COPY_AND_ASSIGN(GraphVisualizer);
 };
@@ -390,14 +389,6 @@ void GraphVisualizer::Print() {
 }
 
 
-GraphVisualizer::GraphVisualizer(std::ostream& os, Zone* zone,
-                                 const Graph* graph)  // NOLINT
-    : zone_(zone),
-      all_(zone, graph),
-      os_(os),
-      graph_(graph) {}
-
-
 std::ostream& operator<<(std::ostream& os, const AsDOT& ad) {
   Zone tmp_zone(ad.graph.zone()->isolate());
   GraphVisualizer(os, &tmp_zone, &ad.graph).Print();