Fix blink_perf.paint regression about tables

third_party/WebKit/Source/core/layout/LayoutTableSection.h

Index: third_party/WebKit/Source/core/layout/LayoutTableSection.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutTableSection.h b/third_party/WebKit/Source/core/layout/LayoutTableSection.h
index 52e5d5dc844c3b0fa61fe1717e71fe800053be86..06b2e597e78d25532c773ac74e355584b01b7f93 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableSection.h
+++ b/third_party/WebKit/Source/core/layout/LayoutTableSection.h
@@ -218,8 +218,6 @@ class CORE_EXPORT LayoutTableSection final : public LayoutTableBoxComponent {
     return m_grid[row].row[effectiveColumn];
   }
   LayoutTableCell* primaryCellAt(unsigned row, unsigned effectiveColumn) {
-    if (effectiveColumn >= numCols(row))

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

I find it strange that this makes a lot of difference. numCols() looks cheap.

Does it help if you rewrite primaryCellAt() as:

    Row& rowVector = m_grid[row].row;
    if (effectiveColumn >= rowVector.size())
      return nullptr;
    return rowVector[effectiveColumn].primaryCell();

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

Done.

-      return nullptr;
     CellStruct& c = m_grid[row].row[effectiveColumn];
     return c.primaryCell();
   }