Revert of Make NavigationScheduler post loading tasks instead of timers

Source/core/loader/NavigationScheduler.h

Index: Source/core/loader/NavigationScheduler.h
diff --git a/Source/core/loader/NavigationScheduler.h b/Source/core/loader/NavigationScheduler.h
index e755265cf207afa5ff463122026729f05a4f16d8..352ae163d569b7793d8ec56aa6d4fe3b324a34d5 100644
--- a/Source/core/loader/NavigationScheduler.h
+++ b/Source/core/loader/NavigationScheduler.h
@@ -34,7 +34,6 @@
 #include "core/CoreExport.h"
 #include "platform/Timer.h"
 #include "platform/heap/Handle.h"
-#include "platform/scheduler/CancellableTaskFactory.h"
 #include "wtf/Forward.h"
 #include "wtf/HashMap.h"
 #include "wtf/Noncopyable.h"
@@ -114,13 +113,13 @@
     bool shouldScheduleReload() const;
     bool shouldScheduleNavigation(const String& url) const;
 
-    void navigateTask();
+    void timerFired(Timer<NavigationScheduler>*);
     void schedule(PassOwnPtrWillBeRawPtr<ScheduledNavigation>);
 
     static bool mustReplaceCurrentItem(LocalFrame* targetFrame);
 
     RawPtrWillBeMember<LocalFrame> m_frame;
-    CancellableTaskFactory m_navigateTaskFactory;
+    Timer<NavigationScheduler> m_timer;
     OwnPtrWillBeMember<ScheduledNavigation> m_redirect;
     int m_navigationDisableCount;
 };