Move Document::m_inStyleRecalc into DocumentLifecycle

Source/core/dom/DocumentLifecycle.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 23 matching lines @@
 #include "wtf/Noncopyable.h"
 
 namespace WebCore {
 
 class DocumentLifecycle {
     WTF_MAKE_NONCOPYABLE(DocumentLifecycle);
 public:
     enum State {
         Uninitialized,
         Inactive,
-        Active,
+
+        // When the document is active, it traverses these states.
+        Attached,

[eseidel, 2014/01/31 01:54:21]

I would call this "clean" or something similar and move it to teh bottom.  We
jump right from "inactive" to "Clean" if necessary, as we progress through the
update steps we get cleaner and cleaner until we're "Clean".

+        InStyleRecalc,
+
+        // Once the document starts shuting down, we cannot return
+        // to the style/layout/rendering states.
         Stopping,
         Stopped,
         Disposed,
     };
 
     DocumentLifecycle();
     ~DocumentLifecycle();
 
+    bool isActive() const { return m_state > Inactive && m_state < Stopping; }
     State state() const { return m_state; }
 
     void advanceTo(State);
 
 private:
     State m_state;
 };
 
 }
 
 #endif