Revert 167826 "Rename text track methods to make way for audio &..."

This CL broke a lot of Media tests and Track tests in Linux bots.
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%2032

> Rename text track methods to make way for audio & video tracks.
> 
> - Rename various text track related methods to explicitly indicate that
>   they apply to text tracks. This is to avoid confusion when audio &
>   video track logic is landed.
> 
> - Renamed TextTrackList::clearOwner() to clearOwnerAndClients() and moved
>   some the client clearing out of HTMLMediaElement and into TextTrackList.
>   This doesn't introduce any change in behavior. It just restores some
>   encapsulation.
> 
> BUG=249427
> TEST=All LayoutTests still pass.
> 
> Review URL: https://codereview.chromium.org/180173002

TBR=acolwell@chromium.org

Review URL: https://codereview.chromium.org/177213015

git-svn-id: svn://svn.chromium.org/blink/trunk@167841 bbb929c8-8fbe-4397-9dbb-9b2b20218538