Clean compositing inputs for location APIs for sticky-affected elements.

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 bcf3fc40763b1652f230aba33a70d8031b07f18a..5c2f9eb007890e1260f3d83d69430555de3d6dc6 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h
+++ b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h
@@ -184,6 +184,8 @@ class CORE_EXPORT LayoutBoxModelObject : public LayoutObject {
   virtual PaintLayerType LayerTypeRequired() const = 0;
   PaintLayerScrollableArea* GetScrollableArea() const;
 
+  bool IsInStickySubtree() const { return is_in_sticky_subtree_; }
+
   virtual void UpdateFromStyle();
 
   // This will work on inlines to return the bounding box of all of the lines'
@@ -546,6 +548,8 @@ class CORE_EXPORT LayoutBoxModelObject : public LayoutObject {
   }
 
   std::unique_ptr<LayoutBoxModelObjectRareData> rare_data_;
+
+  bool is_in_sticky_subtree_;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutBoxModelObject, IsBoxModelObject());