[turbofan] Cleanup Graph and related classes.

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 09a650cce8fbb015f798465ee1f245ae8623c2f9..5c612baf6ebf753af11b87d4277e0e915506799f 100644
--- a/src/compiler/graph-reducer.h
+++ b/src/compiler/graph-reducer.h
@@ -5,13 +5,18 @@
 #ifndef V8_COMPILER_GRAPH_REDUCER_H_
 #define V8_COMPILER_GRAPH_REDUCER_H_
 
-#include "src/compiler/graph.h"
+#include "src/compiler/node-marker.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: