When repeating headers don't use the header offset on the header itself

third_party/WebKit/Source/core/layout/LayoutTableSection.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, 2008, 2009, 2010, 2013 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
@@ skipping 2001 matching lines @@
   if (rowObject.isFirstRowInSectionAfterHeader())
     table()->setRowOffsetFromRepeatingHeader(LayoutUnit());
   // Border spacing from the previous row has pushed this row just past the top
   // of the page, so we must reposition it to the top of the page and avoid any
   // repeating header.
   if (rowIsAtTopOfColumn && offsetFromTopOfPage)
     paginationStrut -= offsetFromTopOfPage.toInt();
 
   // If we have a header group we will paint it at the top of each page,
   // move the rows down to accomodate it.
-  if (header)
+  if (header && header != this)
     paginationStrut += table()->rowOffsetFromRepeatingHeader().toInt();
   rowObject.setPaginationStrut(LayoutUnit(paginationStrut));
 
   // We have inserted a pagination strut before the row. Adjust the logical top
   // and re-lay out. We no longer want to break inside the row, but rather
   // *before* it. From the previous layout pass, there are most likely
   // pagination struts inside some cell in this row that we need to get rid of.
   rowObject.setLogicalTop(rowObject.logicalTop() + paginationStrut);
   layouter.setChildNeedsLayout(&rowObject);
   rowObject.layoutIfNeeded();
@@ skipping 46 matching lines @@
     transformState.flatten();
     FloatRect rect = transformState.lastPlanarQuad().boundingBox();
     rect.setHeight(table()->logicalHeight());
     transformState.setQuad(FloatQuad(rect));
   }
   return LayoutTableBoxComponent::mapToVisualRectInAncestorSpaceInternal(
       ancestor, transformState, flags);
 }
 
 }  // namespace blink