Revert of Revert of 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 8de875030b0e156da4bb7e7b2e0c3d0a7244712c..92717b93ee4d25e89559a8fa65d9a050d4eb70eb 100644
--- a/Source/core/rendering/RenderFlowThread.cpp
+++ b/Source/core/rendering/RenderFlowThread.cpp
@@ -165,8 +165,6 @@
     if (!shouldRepaint(repaintRect) || !hasValidRegionInfo())
         return;
 
-    ForceHorriblySlowRectMapping slowRectMapping(*this); // We can't use layout state to repaint, since the regions are somewhere else.
-
     // We can't use currentFlowThread as it is possible to have interleaved flow threads and the wrong one could be used.
     // Let each columnSet figure out the proper enclosing flow thread.
     CurrentRenderFlowThreadDisabler disabler(view());