[turbofan] delete graph and schedule before register allocation.

src/compiler/schedule.h

Index: src/compiler/schedule.h
diff --git a/src/compiler/schedule.h b/src/compiler/schedule.h
index 5ff554f821e6545f5666e0b3b5b0325f030885b9..1924be55699416600ea30e5bce099fd93cbe6d69 100644
--- a/src/compiler/schedule.h
+++ b/src/compiler/schedule.h
@@ -265,6 +265,8 @@ class Schedule FINAL : public ZoneObject {
   BasicBlockVector rpo_order_;            // Reverse-post-order block list.
   BasicBlock* start_;
   BasicBlock* end_;
+
+  DISALLOW_COPY_AND_ASSIGN(Schedule);
 };
 
 std::ostream& operator<<(std::ostream& os, const Schedule& s);