add 'slow' prefix to RenderObject's firstChild() / lastChild() methods

Source/core/rendering/RenderTableSection.cpp

Index: Source/core/rendering/RenderTableSection.cpp
diff --git a/Source/core/rendering/RenderTableSection.cpp b/Source/core/rendering/RenderTableSection.cpp
index e594892ca244c1416edd9b8852b8d6c6594f41ca..a9d026ae2c83c043f92aba7ae1240e7d0968b347 100644
--- a/Source/core/rendering/RenderTableSection.cpp
+++ b/Source/core/rendering/RenderTableSection.cpp
@@ -127,7 +127,7 @@ void RenderTableSection::addChild(RenderObject* child, RenderObject* beforeChild
             last = lastChild();
         if (last && last->isAnonymous() && !last->isBeforeOrAfterContent()) {
             if (beforeChild == last)
-                beforeChild = last->firstChild();
+                beforeChild = last->slowFirstChild();
             last->addChild(child, beforeChild);
             return;
         }
@@ -1509,7 +1509,7 @@ void RenderTableSection::recalcCells()
             tableRow->setRowIndex(insertionRow);
             setRowLogicalHeightToRowStyleLogicalHeight(m_grid[insertionRow]);
 
-            for (RenderObject* cell = row->firstChild(); cell; cell = cell->nextSibling()) {
+            for (RenderObject* cell = tableRow->firstChild(); cell; cell = cell->nextSibling()) {
                 if (!cell->isTableCell())
                     continue;