Move Document::m_inStyleRecalc into DocumentLifecycle

Source/core/dom/DocumentLifecycle.h

Index: Source/core/dom/DocumentLifecycle.h
diff --git a/Source/core/dom/DocumentLifecycle.h b/Source/core/dom/DocumentLifecycle.h
index c3f919635e833a43521a5a7e401602671935c4f6..24663cc42e0a8b43f8832bef3d5e9f9b3f802f57 100644
--- a/Source/core/dom/DocumentLifecycle.h
+++ b/Source/core/dom/DocumentLifecycle.h
@@ -41,7 +41,13 @@ 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,
@@ -50,6 +56,7 @@ public:
     DocumentLifecycle();
     ~DocumentLifecycle();
 
+    bool isActive() const { return m_state > Inactive && m_state < Stopping; }
     State state() const { return m_state; }
 
     void advanceTo(State);