Intersection Observer first draft

Source/core/layout/LayoutView.h

Index: Source/core/layout/LayoutView.h
diff --git a/Source/core/layout/LayoutView.h b/Source/core/layout/LayoutView.h
index ea2d26fb1293418ec90d06deeb704c0e50177288..46386f95dc17e14df5579f7958a26201d1ef5fc8 100644
--- a/Source/core/layout/LayoutView.h
+++ b/Source/core/layout/LayoutView.h
@@ -43,6 +43,8 @@ namespace blink {
 class DeprecatedPaintLayerCompositor;
 class LayoutQuote;
 
+using IntersectionObserverTargetMap = HashMap<LayoutObject*, FloatRect>;
+
 // The root of the layout tree, corresponding to the CSS initial containing block.
 // It's dimensions match that of the logical viewport (which may be different from
 // the visible viewport in fixed-layout mode), and it is always at position (0,0)
@@ -189,6 +191,10 @@ public:
     // It is very likely you do not want to call this method.
     void setShouldDoFullPaintInvalidationForViewAndAllDescendants();
 
+    void addIntersectionObserverTarget(LayoutObject*);
+    void removeIntersectionObserverTarget(LayoutObject*);
+    void computeIntersectionObservations(const FloatRect&);
+
 private:
     void mapLocalToContainer(const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = nullptr, const PaintInvalidationState* = nullptr) const override;
 
@@ -234,6 +240,8 @@ private:
     OwnPtrWillBePersistent<HitTestCache> m_hitTestCache;
 
     OwnPtrWillBePersistent<PendingSelection> m_pendingSelection;
+
+    IntersectionObserverTargetMap m_intersectionObserverTargets;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutView, isLayoutView());