Adapt and reland old position sticky implementation

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

Index: third_party/WebKit/Source/core/layout/LayoutInline.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutInline.h b/third_party/WebKit/Source/core/layout/LayoutInline.h
index 945a4f5f8dfaef00c62fcaddd1ae4f23310729c8..5398979f8bdd995683ed6e269c53f9b3c89b8ff4 100644
--- a/third_party/WebKit/Source/core/layout/LayoutInline.h
+++ b/third_party/WebKit/Source/core/layout/LayoutInline.h
@@ -245,6 +245,8 @@ private:
 
     PositionWithAffinity positionForPoint(const LayoutPoint&) final;
 
+    LayoutRect frameRectForStickyPositioning() const override final { return LayoutRect(linesBoundingBox()); }

[chrishtr, 2015/11/04 01:55:18]

Rather than adding a new virtual API method to handle differences between block
and inline layout, I think it would be better
to just do type inspection in LayoutBoxModelObject and call either
linesBoundingBox() or frameRect() as appropriate.

[flackr, 2015/11/25 20:47:53]

Done.

+
     IntRect borderBoundingBox() const final
     {
         IntRect boundingBox = linesBoundingBox();