Handle nested position:sticky elements correctly (compositor)

third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp

Index: third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp b/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp
index a241925f30d7005a06a2797d6c20320d986afadc..ee0edae79fb21b6d26ac00dedd72a1918f143df3 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp
@@ -232,20 +232,8 @@ bool CompositingReasonFinder::requiresCompositingForScrollDependentPosition(
   if (layer->sticksToViewport())
     return m_layoutView.frameView()->isScrollable();
 
-  if (layer->layoutObject().style()->position() != EPosition::kSticky)
-    return false;
-
-  // Don't promote nested sticky elements; the compositor can't handle them.
-  // TODO(smcgruer): Add cc nested sticky support (http://crbug.com/672710)
-  PaintLayerScrollableArea* scrollableArea =
-      layer->ancestorOverflowLayer()->getScrollableArea();
-  DCHECK(scrollableArea->stickyConstraintsMap().contains(
-      const_cast<PaintLayer*>(layer)));
-
-  return layer->ancestorOverflowLayer()->scrollsOverflow() &&
-         !scrollableArea->stickyConstraintsMap()
-              .at(const_cast<PaintLayer*>(layer))
-              .hasAncestorStickyElement();
+  return layer->layoutObject().style()->position() == EPosition::kSticky &&
+         layer->ancestorOverflowLayer()->scrollsOverflow();
 }
 
 }  // namespace blink