Make running asanified tests on swarming work on Windows.

Make running asanified tests on swarming work on Windows.

With swarming, the run command gets baked into the .isolate file instead
of going through runtest.py.  Usually, an invocation of test_env.py is
baked into the isolate file. In asan mode, this used to call
asan_symbolize.py, which on Windows doesn't work -- prepend it with
sys.executable to make this work on all platforms.

BUG=451741
Committed: https://crrev.com/b095146c32074b3a96c89e7be2405c77571fdb58
Cr-Commit-Position: refs/heads/master@{#313360}

[Nico, 2015-01-27 20:51:50]

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

[scottmg, 2015-01-27 20:54:49]

lgtm

[Nico, 2015-01-27 20:55:19]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-01-27 20:56:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/877183002/1

[commit-bot: I haz the power, 2015-01-27 21:31:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-27 21:32:56]

Patchset 1 (id:??) landed as
https://crrev.com/b095146c32074b3a96c89e7be2405c77571fdb58
Cr-Commit-Position: refs/heads/master@{#313360}