Revert "Adapt and reland old position sticky implementation from https://codereview.chromium.org/34…

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h

Index: third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
index c9bc87ef4fc426708f524ffd68dd94fce1716073..5ba25a8fdee4bff2c47eab9de4d093e6609fadee 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
+++ b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
@@ -63,17 +63,6 @@ class LayoutBox;
 class PaintLayer;
 class LayoutScrollbarPart;
 
-typedef WTF::HashMap<PaintLayer*, StickyPositionScrollingConstraints> StickyConstraintsMap;
-
-struct PaintLayerScrollableAreaRareData {
-    WTF_MAKE_NONCOPYABLE(PaintLayerScrollableAreaRareData);
-    USING_FAST_MALLOC(PaintLayerScrollableAreaRareData);
-public:
-    PaintLayerScrollableAreaRareData() {}
-
-    StickyConstraintsMap m_stickyConstraintsMap;
-};
-
 // PaintLayerScrollableArea represents the scrollable area of a LayoutBox.
 //
 // To be scrollable, an element requires ‘overflow’ != visible. Note that this
@@ -352,10 +341,6 @@ public:
     bool shouldRebuildVerticalScrollbarLayer() const { return m_rebuildVerticalScrollbarLayer; }
     void resetRebuildScrollbarLayerFlags();
 
-    StickyConstraintsMap& stickyConstraintsMap() { return ensureRareData().m_stickyConstraintsMap; }
-    void invalidateAllStickyConstraints();
-    void invalidateStickyConstraintsFor(PaintLayer*, bool needsCompositingUpdate = true);
-
     DECLARE_VIRTUAL_TRACE();
 
 private:
@@ -391,18 +376,6 @@ private:
 
     void updateCompositingLayersAfterScroll();
 
-    PaintLayerScrollableAreaRareData* rareData()
-    {
-        return m_rareData.get();
-    }
-
-    PaintLayerScrollableAreaRareData& ensureRareData()
-    {
-        if (!m_rareData)
-            m_rareData = adoptPtr(new PaintLayerScrollableAreaRareData());
-        return *m_rareData.get();
-    }
-
     // PaintInvalidationCapableScrollableArea
     LayoutBox& boxForScrollControlPaintInvalidation() const { return box(); }
 
@@ -449,8 +422,6 @@ private:
 
     ScrollAnchor m_scrollAnchor;
 
-    OwnPtr<PaintLayerScrollableAreaRareData> m_rareData;
-
 #if ENABLE(ASSERT)
     bool m_hasBeenDisposed;
 #endif