Adapt and reland old position sticky implementation

third_party/WebKit/Source/core/frame/FrameView.h

Index: third_party/WebKit/Source/core/frame/FrameView.h
diff --git a/third_party/WebKit/Source/core/frame/FrameView.h b/third_party/WebKit/Source/core/frame/FrameView.h
index 4724c13b755576e1d22fda94c4fd46d1fce91e70..a96aad3d7bf22b48d85c96b4befe6b270b49052a 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.h
+++ b/third_party/WebKit/Source/core/frame/FrameView.h
@@ -195,6 +195,11 @@ public:
     const ViewportConstrainedObjectSet* viewportConstrainedObjects() const { return m_viewportConstrainedObjects.get(); }
     bool hasViewportConstrainedObjects() const { return m_viewportConstrainedObjects && m_viewportConstrainedObjects->size() > 0; }
 
+    // Sticky objects.
+    void addStickyPositionObject() { ++m_stickyPositionObjectCount; }
+    void removeStickyPositionObject() { --m_stickyPositionObjectCount; }
+    bool hasStickyPositionObjects() const { return m_stickyPositionObjectCount; }
+
     // Objects with background-attachment:fixed.
     void addBackgroundAttachmentFixedObject(LayoutObject*);
     void removeBackgroundAttachmentFixedObject(LayoutObject*);
@@ -819,6 +824,7 @@ private:
     OwnPtrWillBeMember<ScrollableAreaSet> m_animatingScrollableAreas;
     OwnPtr<ResizerAreaSet> m_resizerAreas;
     OwnPtr<ViewportConstrainedObjectSet> m_viewportConstrainedObjects;
+    unsigned m_stickyPositionObjectCount;
     ViewportConstrainedObjectSet m_backgroundAttachmentFixedObjects;
     OwnPtrWillBeMember<FrameViewAutoSizeInfo> m_autoSizeInfo;