Use tighter typing in table rendering code

Source/core/rendering/FixedTableLayout.cpp

Index: Source/core/rendering/FixedTableLayout.cpp
diff --git a/Source/core/rendering/FixedTableLayout.cpp b/Source/core/rendering/FixedTableLayout.cpp
index 4d1eab50b6bfcbd837bb1be20b1321117862d4c3..25e4b83ffd3f5746cc2a6f0b066df58cfbec8e4a 100644
--- a/Source/core/rendering/FixedTableLayout.cpp
+++ b/Source/core/rendering/FixedTableLayout.cpp
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2002 Lars Knoll (knoll@kde.org)
  *           (C) 2002 Dirk Mueller (mueller@kde.org)
- * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc.
+ * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2013 Apple Inc.

[mstensho (USE GERRIT), 2014/05/20 09:34:39]

I think this header should be left alone or replaced completely with:

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

Can some owners please comment on this?

Anyway, it's not 2013 anymore. :)

You've made this change to quite a few files, but I will refrain from
duplicating this comment at all those instances.

[rune, 2014/05/20 09:45:25]

New files should use the three-line copyright above, existing files should be
left unchanged:

https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/oSaYHvSLg2M

[Inactive, 2014/05/20 11:32:23]

These are not new files so we cannot use the 3-line copyright as far as I know.
I am porting a patch from Apple that was committed in 2013 so I think updating
the Apple copyright lines to add "2013" is the right thing to do as far as I
know?

[pdr., 2014/05/20 16:49:16]

I think we should move this over as this patch does. Feel free to email
blink-dev for more information though, if you'd like to be on the safe side.

  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -137,13 +137,8 @@ int FixedTableLayout::calcWidthArray()
 
     unsigned currentColumn = 0;
 
-    RenderTableRow* firstRow = toRenderTableRow(section->firstChild());
-    for (RenderObject* child = firstRow->firstChild(); child; child = child->nextSibling()) {
-        if (!child->isTableCell())
-            continue;
-
-        RenderTableCell* cell = toRenderTableCell(child);
-
+    RenderTableRow* firstRow = section->firstRow();
+    for (RenderTableCell* cell = firstRow->firstCell(); cell; cell = cell->nextCell()) {
         Length logicalWidth = cell->styleOrColLogicalWidth();
         unsigned span = cell->colSpan();
         int fixedBorderBoxLogicalWidth = 0;
@@ -330,11 +325,8 @@ void FixedTableLayout::willChangeTableLayout()
             RenderTableRow* row = section->rowRendererAt(i);
             if (!row)
                 continue;
-            for (RenderObject* cell = row->firstChild(); cell; cell = cell->nextSibling()) {
-                if (!cell->isTableCell())
-                    continue;
+            for (RenderTableCell* cell = row->firstCell(); cell; cell = cell->nextCell())
                 cell->setPreferredLogicalWidthsDirty();
-            }
         }
     }
 }