Revert of Add template parameter to ElementTraversal to iterate over Elements of a specific type (https://codereview.chromium.org/179333004/)

Reason for revert:
Does not work as intended, I noticed breakages when porting more code to the new API. Reverting until I figure out the problem.

Original issue's description:
> Add template parameter to ElementTraversal to iterate over Elements of a specific type
> 
> Add template parameter to ElementTraversal to iterate over Elements of a
> specific type. The resulting code looks like:
> HTMLTableRowElement* row = Traversal<HTMLTableRowElement>::firstWithin(table);
> 
> This avoids having to traverse generic Elements and then explicitly check their
> tag name to make sure it is a specific Element subclass.
> 
> This CL only updates one file to use this functionality. The rest of the code
> will be ported in a follow-up patch to reduce patch size.
> 
> This patch is based on the following WebKit revision by <antti@apple.com>:
> http://trac.webkit.org/changeset/154481
> 
> R=esprehn@chromium.org, eseidel, esprehn
> BUG=346733
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=167945

TBR=eseidel@chromium.org,esprehn@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=346733

Review URL: https://codereview.chromium.org/182583002

git-svn-id: svn://svn.chromium.org/blink/trunk@167956 bbb929c8-8fbe-4397-9dbb-9b2b20218538