Always anchor to top of the anchor element

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ScrollAnchor_h
 #define ScrollAnchor_h
 
 #include "core/CoreExport.h"
 #include "platform/geometry/LayoutPoint.h"
 #include "platform/heap/Handle.h"
@@ skipping 23 matching lines @@
     void save();
 
     // Scrolls to compensate for any change in the anchor's relative location
     // since the most recent call to save(). Should be called immediately after
     // the scroller has been laid out.
     void restore();
 
     enum class Corner {
         TopLeft = 0,
         TopRight,
-        BottomLeft,
-        BottomRight
     };
     // Which corner of the anchor object we are currently anchored to.
     // Only meaningful if anchorObject() is non-null.
     Corner corner() const { return m_corner; }
 
     DEFINE_INLINE_TRACE() { visitor->trace(m_scroller); }
 
 private:
     void findAnchor();
 
@@ skipping 29 matching lines @@
     // Which corner of m_anchorObject's bounding box to anchor to.
     Corner m_corner;
 
     // Location of m_layoutObject relative to scroller at time of save().
     LayoutPoint m_savedRelativeOffset;
 };
 
 } // namespace blink
 
 #endif // ScrollAnchor_h