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

third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h

Index: third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h
index f686b6257209764313e33d507a606c471448acd0..8609f9b8a1421185ab7c0c486e1c8db92fc9829b 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h
+++ b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h
@@ -26,7 +26,6 @@
 
 #include "core/CoreExport.h"
 #include "core/layout/LayoutObject.h"
-#include "core/page/scrolling/StickyPositionScrollingConstraints.h"
 #include "core/style/ShadowData.h"
 #include "platform/geometry/LayoutRect.h"
 
@@ -65,15 +64,6 @@ enum ContentChangeType {
 
 class InlineFlowBox;
 
-struct LayoutBoxModelObjectRareData {
-    WTF_MAKE_NONCOPYABLE(LayoutBoxModelObjectRareData);
-    USING_FAST_MALLOC(LayoutBoxModelObjectRareData);
-public:
-    LayoutBoxModelObjectRareData() {}
-
-    StickyPositionScrollingConstraints m_stickyPositionScrollingConstraints;
-};
-
 // This class is the base class for all CSS objects.
 //
 // All CSS objects follow the box model object. See THE BOX MODEL section in
@@ -151,12 +141,6 @@ public:
     LayoutSize relativePositionOffset() const;
     LayoutSize relativePositionLogicalOffset() const { return style()->isHorizontalWritingMode() ? relativePositionOffset() : relativePositionOffset().transposedSize(); }
 
-    // Populates StickyPositionConstraints, setting the sticky box rect, containing block rect and updating
-    // the constraint offsets according to the available space.
-    FloatRect computeStickyConstrainingRect() const;
-    void updateStickyPositionConstraints() const;
-    LayoutSize stickyPositionOffset() const;
-
     LayoutSize offsetForInFlowPosition() const;
 
     // IE extensions. Used to calculate offsetWidth/Height.  Overridden by inlines (LayoutFlow)
@@ -344,8 +328,6 @@ protected:
     void styleWillChange(StyleDifference, const ComputedStyle& newStyle) override;
     void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override;
 
-    void invalidateStickyConstraints();
-
 public:
     // These functions are only used internally to manipulate the layout tree structure via remove/insert/appendChildNode.
     // Since they are typically called only to move objects around within anonymous blocks (which only have layers in
@@ -377,18 +359,9 @@ private:
     LayoutUnit computedCSSPadding(const Length&) const;
     bool isBoxModelObject() const final { return true; }
 
-    LayoutBoxModelObjectRareData& ensureRareData()
-    {
-        if (!m_rareData)
-            m_rareData = adoptPtr(new LayoutBoxModelObjectRareData());
-        return *m_rareData.get();
-    }
-
     // The PaintLayer associated with this object.
     // |m_layer| can be nullptr depending on the return value of layerTypeRequired().
     OwnPtr<PaintLayer> m_layer;
-
-    OwnPtr<LayoutBoxModelObjectRareData> m_rareData;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutBoxModelObject, isBoxModelObject());