Add StyleChangeState to get rid of a bunch of static state in the render tree.

Source/WebCore/rendering/RenderObject.cpp

Index: Source/WebCore/rendering/RenderObject.cpp
diff --git a/Source/WebCore/rendering/RenderObject.cpp b/Source/WebCore/rendering/RenderObject.cpp
index fb9f13930b28e669b243333e7b47b64605cf5802..236d82d4c42b2e6ef7622197002dd736626dc07b 100644
--- a/Source/WebCore/rendering/RenderObject.cpp
+++ b/Source/WebCore/rendering/RenderObject.cpp
@@ -118,8 +118,6 @@ struct SameSizeAsRenderObject {
 
 COMPILE_ASSERT(sizeof(RenderObject) == sizeof(SameSizeAsRenderObject), RenderObject_should_stay_small);
 
-bool RenderObject::s_affectsParentBlock = false;

[eseidel, 2013/04/05 01:50:36]

Do we have any clue why these came to be this way?  Were the statics faster?  Do
we have perf concerns for this change?

[esprehn, 2013/04/17 03:29:01]

I had a discussion on IRC with apple folks way back about this and the reason
was apparently because it was easier at the time but nothing specific.

-
 RenderObjectAncestorLineboxDirtySet* RenderObject::s_ancestorLineboxDirtySet = 0;
 
 void* RenderObject::operator new(size_t sz, RenderArena* renderArena)
@@ -1802,7 +1800,8 @@ void RenderObject::setStyle(PassRefPtr<RenderStyle> style)
 
     diff = adjustStyleDifference(diff, contextSensitiveProperties);
 
-    styleWillChange(diff, style.get());
+    StyleChangeState state;
+    styleWillChange(diff, style.get(), state);
     
     RefPtr<RenderStyle> oldStyle = m_style.release();
     setStyleInternal(style);
@@ -1820,7 +1819,7 @@ void RenderObject::setStyle(PassRefPtr<RenderStyle> style)
 
     bool doesNotNeedLayout = !m_parent || isText();
 
-    styleDidChange(diff, oldStyle.get());
+    styleDidChange(diff, oldStyle.get(), state);
 
     // FIXME: |this| might be destroyed here. This can currently happen for a RenderTextFragment when
     // its first-letter block gets an update in RenderTextFragment::styleDidChange. For RenderTextFragment(s),
@@ -1857,7 +1856,7 @@ static inline bool rendererHasBackground(const RenderObject* renderer)
     return renderer && renderer->hasBackground();
 }
 
-void RenderObject::styleWillChange(StyleDifference diff, const RenderStyle* newStyle)
+void RenderObject::styleWillChange(StyleDifference diff, const RenderStyle* newStyle, StyleChangeState& state)
 {
     if (m_style) {
         // If our z-index changes value or our visibility changes,
@@ -1900,7 +1899,7 @@ void RenderObject::styleWillChange(StyleDifference diff, const RenderStyle* newS
             // from the positioned objects list.
             toRenderBox(this)->removeFloatingOrPositionedChildFromBlockLists();
 
-        s_affectsParentBlock = isFloatingOrOutOfFlowPositioned()
+        state.affectsParentBlock = isFloatingOrOutOfFlowPositioned()
             && (!newStyle->isFloating() && !newStyle->hasOutOfFlowPosition())
             && parent() && (parent()->isBlockFlow() || parent()->isRenderInline());
 
@@ -1914,8 +1913,7 @@ void RenderObject::styleWillChange(StyleDifference diff, const RenderStyle* newS
         setHasOverflowClip(false);
         setHasTransform(false);
         setHasReflection(false);
-    } else
-        s_affectsParentBlock = false;
+    }
 
     if (view()->frameView()) {
         bool shouldBlitOnFixedBackgroundImage = false;
@@ -1965,9 +1963,9 @@ static inline bool areCursorsEqual(const RenderStyle* a, const RenderStyle* b)
     return a->cursor() == b->cursor() && (a->cursors() == b->cursors() || areNonIdenticalCursorListsEqual(a, b));
 }
 
-void RenderObject::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
+void RenderObject::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle, const StyleChangeState& state)
 {
-    if (s_affectsParentBlock)
+    if (state.affectsParentBlock)
         handleDynamicFloatPositionChange();
 
 #if ENABLE(SVG)