Revert Disable Rotation on Login Pages

Revert Disable Rotation on Login Pages
Revert "This change is intended to M-43. Currently screen rotation animations expose a bug, causing the login screen to not be useable.

Disable rotation animations while a user is not logged in. This will be later reverted on M-44 where a fix to the underlying issue will be landed."

This reverts commit 274e83a41a63c1746203bc1cee8cefd07ae821c9.
Original review: https://codereview.chromium.org/1139793003/

The underlying bug was fixed via: https://codereview.chromium.org/1125283015/

TBR=oshima@chromium.org
BUG=chrome-os-partner:40118
Committed: https://crrev.com/d30c42fcebbeee085a6fbdfef9c98cf02d02c3bd
Cr-Commit-Position: refs/heads/master@{#330737}

[jonross, 2015-05-20 14:48:17]

The CQ bit was checked by jonross@chromium.org

[commit-bot: I haz the power, 2015-05-20 14:48:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1145963003/1

[commit-bot: I haz the power, 2015-05-20 15:27:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-20 15:29:14]

Patchset 1 (id:??) landed as
https://crrev.com/d30c42fcebbeee085a6fbdfef9c98cf02d02c3bd
Cr-Commit-Position: refs/heads/master@{#330737}