update webdriver for firefox 8 support

firefox version 8 went to release track today.
webdriver (selenium) in third_party doesn't know how
to talk to firefox 8.

this change updates webdriver to latest RC.
with this change, I've successfully run browser tests against
 firefox 7 (old)
 firefox 8 (release, beta)

firefox 9 (aurora) still doesn't work

[Jasvir, 2011-11-08 21:16:39]

LGTM++

Are you able to test if the tests run successfully FF5 and 6 too?

[felix8a, 2011-11-08 21:40:37]

yes, ff5 and ff6 work fine.

On Tue, Nov 8, 2011 at 13:16, <jasvir@gmail.com> wrote:

> LGTM++
>
> Are you able to test if the tests run successfully FF5 and 6 too?
>
>
>
http://codereview.appspot.com/**5361045/<http://codereview.appspot.com/5361045/>
>

[felix8a, 2011-11-08 21:57:00]

@r4665