[turbofan] Cleanup Schedule and related classes.

src/compiler/scheduler.h

Index: src/compiler/scheduler.h
diff --git a/src/compiler/scheduler.h b/src/compiler/scheduler.h
index 9da0b6daa49d93d31c53d8d6a0a43a0762c2a46a..886b755438fc675e198b6012dc0a4d93a870fb9e 100644
--- a/src/compiler/scheduler.h
+++ b/src/compiler/scheduler.h
@@ -7,6 +7,7 @@
 
 #include "src/v8.h"
 
+#include "src/compiler/node.h"
 #include "src/compiler/opcodes.h"
 #include "src/compiler/schedule.h"
 #include "src/compiler/zone-pool.h"
@@ -16,10 +17,13 @@ namespace v8 {
 namespace internal {
 namespace compiler {
 
+// Forward declarations.
 class CFGBuilder;
 class ControlEquivalence;
+class Graph;
 class SpecialRPONumberer;
 
+
 // Computes a schedule from a graph, placing nodes into basic blocks and
 // ordering the basic blocks in the special RPO order.
 class Scheduler {