Remove unneeded flow thread awareness from accumulateOffsetTowardsAncestor().

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index 63e83e3d8eff1a0b96387ac499894f9d9a82d102..9bc19912928ed16f66eae339bed54da7da816988 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -1341,17 +1341,12 @@ static inline const RenderLayer* accumulateOffsetTowardsAncestor(const RenderLay
     const RenderLayerModelObject* renderer = layer->renderer();
     EPosition position = renderer->style()->position();
 
-    // FIXME: Special casing RenderFlowThread so much for fixed positioning here is not great.
-    RenderFlowThread* fixedFlowThreadContainer = position == FixedPosition ? renderer->flowThreadContainingBlock() : 0;
-    if (fixedFlowThreadContainer && !fixedFlowThreadContainer->isOutOfFlowPositioned())
-        fixedFlowThreadContainer = 0;
-
     // FIXME: Positioning of out-of-flow(fixed, absolute) elements collected in a RenderFlowThread
     // may need to be revisited in a future patch.
     // If the fixed renderer is inside a RenderFlowThread, we should not compute location using localToAbsolute,
     // since localToAbsolute maps the coordinates from flow thread to regions coordinates and regions can be
     // positioned in a completely different place in the viewport (RenderView).
-    if (position == FixedPosition && !fixedFlowThreadContainer && (!ancestorLayer || ancestorLayer == renderer->view()->layer())) {
+    if (position == FixedPosition && (!ancestorLayer || ancestorLayer == renderer->view()->layer())) {
         // If the fixed layer's container is the root, just add in the offset of the view. We can obtain this by calling
         // localToAbsolute() on the RenderView.
         FloatPoint absPos = renderer->localToAbsolute(FloatPoint(), IsFixed);
@@ -1362,7 +1357,7 @@ static inline const RenderLayer* accumulateOffsetTowardsAncestor(const RenderLay
     // For the fixed positioned elements inside a render flow thread, we should also skip the code path below
     // Otherwise, for the case of ancestorLayer == rootLayer and fixed positioned element child of a transformed
     // element in render flow thread, we will hit the fixed positioned container before hitting the ancestor layer.
-    if (position == FixedPosition && !fixedFlowThreadContainer) {
+    if (position == FixedPosition) {
         // For a fixed layers, we need to walk up to the root to see if there's a fixed position container
         // (e.g. a transformed layer). It's an error to call convertToLayerCoords() across a layer with a transform,
         // so we should always find the ancestor at or before we find the fixed position container.