Fix blink_perf.paint regression about tables

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

Index: third_party/WebKit/Source/core/layout/LayoutTable.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutTable.cpp b/third_party/WebKit/Source/core/layout/LayoutTable.cpp
index a541b242260e9fc510be933094d0f12474574e54..d459b3903bdb3e619256699690a2843cc381c83d 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTable.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTable.cpp
@@ -1445,7 +1445,9 @@ LayoutTableCell* LayoutTable::cellAbove(const LayoutTableCell* cell) const {
   if (section) {
     unsigned effCol =
         absoluteColumnToEffectiveColumn(cell->absoluteColumnIndex());
-    return section->primaryCellAt(rAbove, effCol);
+    return effCol < section->numCols(rAbove)
+               ? section->primaryCellAt(rAbove, effCol)
+               : nullptr;
   }
   return nullptr;
 }
@@ -1471,7 +1473,9 @@ LayoutTableCell* LayoutTable::cellBelow(const LayoutTableCell* cell) const {
   if (section) {
     unsigned effCol =
         absoluteColumnToEffectiveColumn(cell->absoluteColumnIndex());
-    return section->primaryCellAt(rBelow, effCol);
+    return effCol < section->numCols(rBelow)
+               ? section->primaryCellAt(rBelow, effCol)
+               : nullptr;
   }
   return nullptr;
 }
@@ -1486,9 +1490,7 @@ LayoutTableCell* LayoutTable::cellBefore(const LayoutTableCell* cell) const {
     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 {
@@ -1496,7 +1498,10 @@ LayoutTableCell* LayoutTable::cellAfter(const LayoutTableCell* cell) const {
 
   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,