Avoid unnecessary cell layout on nested percent height tables

third_party/WebKit/Source/core/layout/LayoutTable.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.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
@@ skipping 433 matching lines @@
 }
 
 void LayoutTable::layoutSection(LayoutTableSection& section,
                                 SubtreeLayoutScope& layouter,
                                 LayoutUnit logicalLeft) {
   section.setLogicalLocation(LayoutPoint(logicalLeft, logicalHeight()));
   if (m_columnLogicalWidthChanged)
     layouter.setChildNeedsLayout(&section);
   if (!section.needsLayout())
     markChildForPaginationRelayoutIfNeeded(section, layouter);
-  section.layoutIfNeeded();
-  int sectionLogicalHeight = section.calcRowLogicalHeight();
-  section.setLogicalHeight(LayoutUnit(sectionLogicalHeight));
+  if (section.needsLayout()) {
+    section.layout();
+    section.setLogicalHeight(LayoutUnit(section.calcRowLogicalHeight()));
+  }
   if (view()->layoutState()->isPaginated())
     updateFragmentationInfoForChild(section);
-  setLogicalHeight(logicalHeight() + sectionLogicalHeight);
+  setLogicalHeight(logicalHeight() + section.logicalHeight());
 }
 
 LayoutUnit LayoutTable::logicalHeightFromStyle() const {
   LayoutUnit computedLogicalHeight;
   Length logicalHeightLength = style()->logicalHeight();
   if (logicalHeightLength.isIntrinsic() ||
       (logicalHeightLength.isSpecified() && logicalHeightLength.isPositive())) {
     computedLogicalHeight =
         convertStyleLogicalHeightToComputedHeight(logicalHeightLength);
   }
@@ skipping 24 matching lines @@
 void LayoutTable::distributeExtraLogicalHeight(int extraLogicalHeight) {
   if (extraLogicalHeight <= 0)
     return;
 
   // FIXME: Distribute the extra logical height between all table sections
   // instead of giving it all to the first one.
   if (LayoutTableSection* section = firstBody())
     extraLogicalHeight -=
         section->distributeExtraLogicalHeightToRows(extraLogicalHeight);
 
-  // FIXME: We really would like to enable this ASSERT to ensure that all the
-  // extra space has been distributed.
+  // crbug.com/690087: We really would like to enable this ASSERT to ensure that
+  // all the extra space has been distributed.
   // However our current distribution algorithm does not round properly and thus
   // we can have some remaining height.
   // ASSERT(!topSection() || !extraLogicalHeight);
 }
 
 void LayoutTable::simplifiedNormalFlowLayout() {
   // FIXME: We should walk through the items in the tree in tree order to do the
   // layout here instead of walking through individual parts of the tree.
   // crbug.com/442737
   for (auto& caption : m_captions)
@@ skipping 1172 matching lines @@
 }
 
 LayoutUnit LayoutTable::paddingRight() const {
   if (collapseBorders())
     return LayoutUnit();
 
   return LayoutBlock::paddingRight();
 }
 
 }  // namespace blink