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

Source/core/rendering/RenderTable.cpp

Index: Source/core/rendering/RenderTable.cpp
diff --git a/Source/core/rendering/RenderTable.cpp b/Source/core/rendering/RenderTable.cpp
index cb7d532431be16b1e7da0bc6d5cd9064c295c337..8980b17d8798b7e85afba7bb7c58a020a9c1e638 100644
--- a/Source/core/rendering/RenderTable.cpp
+++ b/Source/core/rendering/RenderTable.cpp
@@ -197,7 +197,7 @@ void RenderTable::addChild(RenderObject* child, RenderObject* beforeChild)
         lastBox = lastBox->parent();
     if (lastBox && lastBox->isAnonymous() && !isAfterContent(lastBox)) {
         if (beforeChild == lastBox)
-            beforeChild = lastBox->firstChild();
+            beforeChild = lastBox->slowFirstChild();
         lastBox->addChild(child, beforeChild);
         return;
     }
@@ -602,10 +602,10 @@ void RenderTable::recalcCollapsedBorders()
     for (RenderObject* section = firstChild(); section; section = section->nextSibling()) {
         if (!section->isTableSection())
             continue;
-        for (RenderObject* row = section->firstChild(); row; row = row->nextSibling()) {
+        for (RenderObject* row = toRenderTableSection(section)->firstChild(); row; row = row->nextSibling()) {
             if (!row->isTableRow())
                 continue;
-            for (RenderObject* cell = row->firstChild(); cell; cell = cell->nextSibling()) {
+            for (RenderObject* cell = toRenderTableRow(row)->firstChild(); cell; cell = cell->nextSibling()) {
                 if (!cell->isTableCell())
                     continue;
                 ASSERT(toRenderTableCell(cell)->table() == this);