Content of cell should avoid repeating headers when it straddles multiple pages

third_party/WebKit/Source/core/layout/LayoutTableRow.cpp

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2013
 *                Apple Inc.
  *               All rights reserved.
  *
@@ skipping 294 matching lines @@
   // The cell and the row share the section's coordinate system. However
   // the visual overflow should be determined in the coordinate system of
   // the row, that's why we shift it below.
   LayoutUnit cellOffsetLogicalTopDifference =
       cell->location().y() - location().y();
   cellVisualOverflowRect.move(LayoutUnit(), cellOffsetLogicalTopDifference);
 
   addContentsVisualOverflow(cellVisualOverflowRect);
 }
 
+bool LayoutTableRow::isFirstRowInSectionAfterHeader() const {
+  // If there isn't room for at least one content row on a page after the
+  // header group, then we won't repeat the header on each page.
+  // https://drafts.csswg.org/css-tables-3/#repeated-headers reads like
+  // it wants us to drop headers on only the pages that a single row
+  // won't fit but we avoid the complexity of that reading until it
+  // is clarified. Tracked by crbug.com/675904
+  LayoutTableSection* header = table()->header();

[mstensho (USE GERRIT), 2016/12/20 11:47:00]

Might want to do an early return for rowIndex()

if (rowIndex())
  return false;

[rhogan, 2016/12/20 16:06:37]

return !rowIndex() && ..; returns just as quickly no? Or is it just about
readability?

[mstensho (USE GERRIT), 2016/12/20 16:50:36]

I was thinking that you could put it in front of the declaration of 'header'.
And THEN it would be WAAAAAAAAY faster for all rows but the first. :)

Also, slightly more readable, IMHO.

[mstensho (USE GERRIT), 2016/12/20 18:20:54]

Did you mean to address this too?

+  return !rowIndex() && header && table()->sectionAbove(section()) == header &&
+         header->getPaginationBreakability() != AllowAnyBreaks;
+}
+
 }  // namespace blink