Paint backgrounds of a table section/row in one display item

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 287 matching lines @@
   if (cell->rowSpan() == 1)
     return;
 
   // Cells only generates visual overflow.
   LayoutRect cellVisualOverflowRect =
       cell->visualOverflowRectForPropagation(styleRef());
 
   // 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);
+  cellVisualOverflowRect.moveBy(-location());
+  addContentsVisualOverflow(cellVisualOverflowRect);
 
-  addContentsVisualOverflow(cellVisualOverflowRect);
+  // Table row paints its background behind cells. If the cell spans multiple
+  // rows, the row's visual rect should be expanded to cover the cell.
+  if (styleRef().hasBackground()) {
+    LayoutRect cellBackgroundRect = cell->frameRect();
+    cellBackgroundRect.moveBy(-location());
+    addSelfVisualOverflow(cellBackgroundRect);
+  }
 }
 
 bool LayoutTableRow::isFirstRowInSectionAfterHeader() const {
   // If there isn't room on the page for at least one content row 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
   if (rowIndex())
     return false;
   LayoutTableSection* header = table()->header();
   return header && table()->sectionAbove(section()) == header &&
          header->getPaginationBreakability() != AllowAnyBreaks;
 }
 
 }  // namespace blink