Adapt and reland old position sticky implementation

Source/core/paint/DeprecatedPaintLayer.cpp

Index: Source/core/paint/DeprecatedPaintLayer.cpp
diff --git a/Source/core/paint/DeprecatedPaintLayer.cpp b/Source/core/paint/DeprecatedPaintLayer.cpp
index 561020b810667e0304e8f6c13af08d4f3a715cec..f62aae8c10dbe6299fbe966773f6e5e8268f10b4 100644
--- a/Source/core/paint/DeprecatedPaintLayer.cpp
+++ b/Source/core/paint/DeprecatedPaintLayer.cpp
@@ -313,7 +313,16 @@ void DeprecatedPaintLayer::dirtyAncestorChainHasSelfPaintingLayerDescendantStatu
 
 bool DeprecatedPaintLayer::scrollsWithViewport() const
 {
-    return layoutObject()->style()->position() == FixedPosition && layoutObject()->containerForFixedPosition() == layoutObject()->view();
+    return (layoutObject()->style()->position() == FixedPosition && layoutObject()->containerForFixedPosition() == layoutObject()->view())
+        || (layoutObject()->style()->position() == StickyPosition && !ancestorScrollingLayer());
+}
+
+bool DeprecatedPaintLayer::scrollsWithScrollAncestor() const
+{
+    // TODO(flackr): This could check if the ancestor scroller for this layer is scrollable and
+    // composited but this would need to be determined before the composite phase as it's used
+    // as a compositing reason.

[flackr, 2015/09/15 21:13:11]

Is there an easy way to check the scroll ancestor before the ancestor depending
compositing inputs?

+    return layoutObject()->style()->position() == StickyPosition;
 }
 
 bool DeprecatedPaintLayer::scrollsWithRespectTo(const DeprecatedPaintLayer* other) const