Fix blink_perf.paint regression about 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 1427 matching lines @@
     if (section) {
       ASSERT(section->numRows());
       rAbove = section->numRows() - 1;
     }
   }
 
   // Look up the cell in the section's grid, which requires effective col index
   if (section) {
     unsigned effCol =
         absoluteColumnToEffectiveColumn(cell->absoluteColumnIndex());
-    return section->primaryCellAt(rAbove, effCol);
+    return effCol < section->numCols(rAbove)
+               ? section->primaryCellAt(rAbove, effCol)
+               : nullptr;
   }
   return nullptr;
 }
 
 LayoutTableCell* LayoutTable::cellBelow(const LayoutTableCell* cell) const {
   recalcSectionsIfNeeded();
 
   // Find the section and row to look in
   unsigned r = cell->rowIndex() + cell->rowSpan() - 1;
   LayoutTableSection* section = nullptr;
   unsigned rBelow = 0;
   if (r < cell->section()->numRows() - 1) {
     // The cell is not in the last row, so use the next row in the section.
     section = cell->section();
     rBelow = r + 1;
   } else {
     section = sectionBelow(cell->section(), SkipEmptySections);
     if (section)
       rBelow = 0;
   }
 
   // Look up the cell in the section's grid, which requires effective col index
   if (section) {
     unsigned effCol =
         absoluteColumnToEffectiveColumn(cell->absoluteColumnIndex());
-    return section->primaryCellAt(rBelow, effCol);
+    return effCol < section->numCols(rBelow)
+               ? section->primaryCellAt(rBelow, effCol)
+               : nullptr;
   }
   return nullptr;
 }
 
 LayoutTableCell* LayoutTable::cellBefore(const LayoutTableCell* cell) const {
   recalcSectionsIfNeeded();
 
   LayoutTableSection* section = cell->section();
   unsigned effCol =
       absoluteColumnToEffectiveColumn(cell->absoluteColumnIndex());
   if (!effCol)
     return nullptr;
 
   // If we hit a colspan back up to a real cell.
-  LayoutTableSection::CellStruct& prevCell =
-      section->cellAt(cell->rowIndex(), effCol - 1);
-  return prevCell.primaryCell();
+  return section->primaryCellAt(cell->rowIndex(), effCol - 1);

[mstensho (USE GERRIT), 2017/01/20 10:02:04]

This is just clean-up, right?

[a.suchit, 2017/01/23 06:35:32]

yes

 }
 
 LayoutTableCell* LayoutTable::cellAfter(const LayoutTableCell* cell) const {
   recalcSectionsIfNeeded();
 
   unsigned effCol = absoluteColumnToEffectiveColumn(
       cell->absoluteColumnIndex() + cell->colSpan());
-  return cell->section()->primaryCellAt(cell->rowIndex(), effCol);
+  unsigned row = cell->rowIndex();
+  LayoutTableSection* section = cell->section();
+  return effCol < section->numCols(row) ? section->primaryCellAt(row, effCol)
+                                        : nullptr;
 }
 
 int LayoutTable::baselinePosition(FontBaseline baselineType,
                                   bool firstLine,
                                   LineDirectionMode direction,
                                   LinePositionMode linePositionMode) const {
   ASSERT(linePositionMode == PositionOnContainingLine);
   int baseline = firstLineBoxBaseline();
   if (baseline != -1) {
     if (isInline())
@@ skipping 178 matching lines @@
 }
 
 LayoutUnit LayoutTable::paddingRight() const {
   if (collapseBorders())
     return LayoutUnit();
 
   return LayoutBlock::paddingRight();
 }
 
 }  // namespace blink