Change chrome_tests.py to run 'run-webkit-tests' script.

Change chrome_tests.py to run 'run-webkit-tests' script.

Instead of going through the Chromium's script 'run_webkit_tests.py'
that lives in webkit/tools/layout_tests and it is just a wrapper around
'run-webkit-tests', call the later directly from
third_party/WebKit/Tools/Scripts/.

As we are removing webkit/ directory, this change is also necessary.

BUG=338338
TEST=None
R=dpranke@chromium.org,bruening@chromium.org

Committed: https://crrev.com/b62734424a2b90ccf2bdb11a874f774fb15cccaf
Cr-Commit-Position: refs/heads/master@{#297467}

[tfarina, 2014-09-27 02:18:41]

This is the last reference I found with 'git grep run_webkit'.

PTAL.

[Dirk Pranke, 2014-09-27 02:30:46]

lgtm

[Timur Iskhodzhanov, 2014-09-30 09:19:17]

timurrrr@chromium.org changed reviewers:
+ thestig@chromium.org, timurrrr@chromium.org

[Timur Iskhodzhanov, 2014-09-30 09:19:18]

thestig@ might want to review this.  Oh, he's OOO and I can't add him to the
list of reviewers, nevermind.

The change LGTM at the first glance, please watch the bot to make sure it
doesn't blow up after committing.

[Alexander Potapenko, 2014-09-30 09:21:03]

On 2014/09/30 09:19:18, Timur Iskhodzhanov wrote:
> thestig@ might want to review this.  Oh, he's OOO and I can't add him to the
> list of reviewers, nevermind.
> 
> The change LGTM at the first glance, please watch the bot to make sure it
> doesn't blow up after committing.

LGTM, too

[tfarina, 2014-09-30 17:51:39]

The CQ bit was checked by tfarina@chromium.org

[commit-bot: I haz the power, 2014-09-30 17:52:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/608593007/1

[commit-bot: I haz the power, 2014-09-30 18:57:21]

Committed patchset #1 (id:1) as 035c16bad2c8db4e61ff80906052b86f5af248b6

[commit-bot: I haz the power, 2014-09-30 18:58:06]

Patchset 1 (id:??) landed as
https://crrev.com/b62734424a2b90ccf2bdb11a874f774fb15cccaf
Cr-Commit-Position: refs/heads/master@{#297467}