Track reasons for |Node::SetNeedsStyleRecalc|

Source/core/dom/Node.h

Index: Source/core/dom/Node.h
diff --git a/Source/core/dom/Node.h b/Source/core/dom/Node.h
index 98ea05cb5beb6899d4cedf83dd752c80eb693edb..3d287830c9498e3e10e7280cd2d53549ba74f90b 100644
--- a/Source/core/dom/Node.h
+++ b/Source/core/dom/Node.h
@@ -28,6 +28,7 @@
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
 #include "core/dom/MutationObserver.h"
 #include "core/dom/SimulatedClickOptions.h"
+#include "core/dom/StyleChangeReason.h"
 #include "core/dom/TreeScope.h"
 #include "core/dom/TreeShared.h"
 #include "core/editing/EditingBoundary.h"
@@ -354,7 +355,7 @@ public:
     void setChildNeedsStyleRecalc() { setFlag(ChildNeedsStyleRecalcFlag); }
     void clearChildNeedsStyleRecalc() { clearFlag(ChildNeedsStyleRecalcFlag); }
 
-    void setNeedsStyleRecalc(StyleChangeType);
+    void setNeedsStyleRecalc(StyleChangeReason, StyleChangeType);

[pdr., 2014/09/06 22:36:27]

Do we actually need both StyleChangeReason and StyleChangeType?

There is nearly a 1:1 mapping between the two already (only 6 exceptions and
they are easy to work around with more detailed reasons). This would just
require a few helper static functions in StyleChangeReasons such as
isNoStyleChange(StyleChangeReason), isLocalStyleChange(StyleChangeReason), etc.

[kouhei (in TOK), 2014/09/06 23:10:34]

Hmm... this is a hard question.
I think we should have both to avoid repeating mistakes of InvalidationReason
and DocumentLifeCycle. By having both, we keep instrumentation flags and logic
flags apart.

     void clearNeedsStyleRecalc();
 
     bool childNeedsDistributionRecalc() const { return getFlag(ChildNeedsDistributionRecalcFlag); }