Run Blink unit tests on the Clang ToT bots

Run Blink unit tests on the Clang ToT bots

These have been good indicators of miscompiles before, so let's get
them on the ToT bots.

BUG=452726
R=thakis@chromium.org

Committed: https://chromium.googlesource.com/chromium/src/+/5974b3bc1c0b1de265566332215c67122d782a06

[hans, 2015-08-21 01:18:47]

hans@chromium.org changed reviewers:
+ thakis@chromium.org

[hans, 2015-08-21 01:18:47]

ptal when you're around.

[Nico, 2015-08-21 01:40:24]

On 2015/08/21 01:18:47, hans wrote:
> ptal when you're around.

Lgtm

No swarming? Should we run them on the pinned win/clang bots too?

[hans, 2015-08-21 17:42:18]

On 2015/08/21 01:40:24, Nico (on vacation Thu Aug 20) wrote:
> On 2015/08/21 01:18:47, hans wrote:
> > ptal when you're around.
> 
> Lgtm
> 
> No swarming?

I copy-pasted from chromium.webkit.json, and they don't seem to be swarmed there
so I have know idea if that works?

> Should we run them on the pinned win/clang bots too?

Sure, why not.

[hans, 2015-08-21 17:57:39]

I'll land this now, we can try swarming later.

[hans, 2015-08-21 17:59:49]

Committed patchset #2 (id:20001) manually as
5974b3bc1c0b1de265566332215c67122d782a06 (presubmit successful).