Divorce PaintInvalidationState from LayoutState

Source/core/rendering/RenderFlowThread.cpp

Index: Source/core/rendering/RenderFlowThread.cpp
diff --git a/Source/core/rendering/RenderFlowThread.cpp b/Source/core/rendering/RenderFlowThread.cpp
index 4e068f879210602f1dc2579f42b3da45df79c556..027dfd54f0b5c7797667b6ca254c1352562681a6 100644
--- a/Source/core/rendering/RenderFlowThread.cpp
+++ b/Source/core/rendering/RenderFlowThread.cpp
@@ -165,8 +165,6 @@ void RenderFlowThread::repaintRectangleInRegions(const LayoutRect& repaintRect)
     if (!shouldRepaint(repaintRect) || !hasValidRegionInfo())
         return;
 
-    ForceHorriblySlowRectMapping slowRectMapping(*this); // We can't use layout state to repaint, since the regions are somewhere else.

[Julien - ping for review, 2014/07/02 00:27:28]

Is this really solved?

[leviw_travelin_and_unemployed, 2014/07/02 00:41:02]

You'll notice from the function prototype that we don't have an
InvalidationTreeWalkState on the stack, so we have nothing to disable.

-
     // We can't use currentFlowThread as it is possible to have interleaved flow threads and the wrong one could be used.
     // Let each region figure out the proper enclosing flow thread.
     CurrentRenderFlowThreadDisabler disabler(view());