Minor modification to roll_webgl_conformance.py

Minor modification to roll_webgl_conformance.py

1) add optional linux bot
2) set default to not starting try jobs dry run. This is because most
rolls we need to update test expectations.

BUG=583702
TEST=
R=kbr@chromium.org
NOTRY=true

Committed: https://crrev.com/3eaa0918dbba4654a74061c706052b0492cd0a98
Cr-Commit-Position: refs/heads/master@{#387757}

[Zhenyao Mo, 2016-04-15 23:55:18]

PTAL

[Ken Russell (switch to Gerrit), 2016-04-15 23:56:17]

lgtm

[Zhenyao Mo, 2016-04-15 23:56:35]

The CQ bit was checked by zmo@chromium.org

[commit-bot: I haz the power, 2016-04-15 23:57:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1889403003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1889403003/20001

[commit-bot: I haz the power, 2016-04-16 00:03:17]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-04-16 00:04:35]

Description was changed from

==========
Minor modification to roll_webgl_conformance.py

1) add optional linux bot
2) set default to not starting try jobs dry run. This is because most
rolls we need to update test expectations.

BUG=583702
TEST=
R=kbr@chromium.org
NOTRY=true
==========

to

==========
Minor modification to roll_webgl_conformance.py

1) add optional linux bot
2) set default to not starting try jobs dry run. This is because most
rolls we need to update test expectations.

BUG=583702
TEST=
R=kbr@chromium.org
NOTRY=true

Committed: https://crrev.com/3eaa0918dbba4654a74061c706052b0492cd0a98
Cr-Commit-Position: refs/heads/master@{#387757}
==========

[commit-bot: I haz the power, 2016-04-16 00:04:36]

Patchset 2 (id:??) landed as
https://crrev.com/3eaa0918dbba4654a74061c706052b0492cd0a98
Cr-Commit-Position: refs/heads/master@{#387757}