Clean up break-inside restriction propagation from table headers.

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 1032 matching lines @@
 
   // Page / column breakability inside block-level objects.
   enum PaginationBreakability {
     AllowAnyBreaks,  // No restrictions on breaking. May examine children to
                      // find possible break points.
     ForbidBreaks,  // Forbid breaks inside this object. Content cannot be split
                    // nicely into smaller pieces.
     AvoidBreaks    // Preferably avoid breaks. If not possible, examine children
                    // to find possible break points.
   };
-  PaginationBreakability getPaginationBreakability() const;
+  virtual PaginationBreakability getPaginationBreakability() const;
 
   LayoutRect localCaretRect(
       InlineBox*,
       int caretOffset,
       LayoutUnit* extraWidthToEndOfLine = nullptr) override;
 
   virtual LayoutRect overflowClipRect(
       const LayoutPoint& location,
       OverlayScrollbarClipBehavior = IgnoreOverlayScrollbarSize) const;
   LayoutRect clipRect(const LayoutPoint& location) const;
@@ skipping 549 matching lines @@
 
 inline bool LayoutBox::isForcedFragmentainerBreakValue(EBreak breakValue) {
   return breakValue == BreakColumn || breakValue == BreakLeft ||
          breakValue == BreakPage || breakValue == BreakRecto ||
          breakValue == BreakRight || breakValue == BreakVerso;
 }
 
 }  // namespace blink
 
 #endif  // LayoutBox_h