Convert nacl_loader_unittests to run exclusively on Swarming

Convert nacl_loader_unittests to run exclusively on Swarming

Remove apparently unused stuff from the existing isolate file
and make it work on Mac and Windows.

0 configs already ran on Swarming
24 used to run locally and were converted:
- chromium.chromiumos.json: Linux ChromiumOS Ozone Tests (1)
- chromium.chromiumos.json: Linux ChromiumOS Tests (1)
- chromium.chromiumos.json: Linux ChromiumOS Tests (dbg)(1)
- chromium.fyi.json: ClangToTLinux tester
- chromium.fyi.json: Linux Trusty
- chromium.fyi.json: Linux Trusty (dbg)
- chromium.linux.json: Linux Tests
- chromium.linux.json: Linux Tests (dbg)(1)
- chromium.linux.json: Linux Tests (dbg)(1)(32)
- chromium.mac.json: Mac10.10 Tests
- chromium.mac.json: Mac10.6 Tests
- chromium.mac.json: Mac10.8 Tests
- chromium.mac.json: Mac10.9 Tests
- chromium.mac.json: Mac10.9 Tests (dbg)
- chromium.memory.fyi.json: Linux ChromeOS MSan Tests
- chromium.memory.fyi.json: Linux MSan Tests
- chromium.memory.json: Linux Chromium OS ASan LSan Tests (1)
- chromium.webkit.json: Linux ChromiumOS Tests (1)
- chromium.webkit.json: Linux ChromiumOS Tests (dbg)(1)
- chromium.win.json: Vista Tests (1)
- chromium.win.json: Win 7 Tests x64 (1)
- chromium.win.json: Win7 Tests (1)
- chromium.win.json: Win7 Tests (dbg)(1)
- chromium.win.json: XP Tests (1)

Ran:
  ./manage.py --convert nacl_loader_unittests

BUG=98637
Committed: https://crrev.com/43c6927492ad9204c02801095a83989cd9771305
Cr-Commit-Position: refs/heads/master@{#337314}

[Nico, 2015-07-03 05:04:17]

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

[Nico, 2015-07-03 05:04:18]

maruel: everything

[M-A Ruel, 2015-07-03 13:54:34]

lgtm

[Nico, 2015-07-03 15:36:07]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-07-03 15:36:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209213003/20001

[commit-bot: I haz the power, 2015-07-03 15:39:06]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-07-03 15:40:01]

Patchset 2 (id:??) landed as
https://crrev.com/43c6927492ad9204c02801095a83989cd9771305
Cr-Commit-Position: refs/heads/master@{#337314}