Merge 95551 - [ChromeOS] Assorted WebUI login fixes.

Merge 95551 - [ChromeOS] Assorted WebUI login fixes.

- Respect account settings by using the users list and other flags passed into
  WebUILoginDisplay::Init;
- Limit max 5 users to avoid scrolling in account picker;
- Increase account picker width to 1100px to avoid crop on user pods;
- Properly remove a user, i.e. go through UserManager::RemoveUser instead
  of delete it directly using RemoveUserFromList;
- Improve the tab order;
- Switch to Gaia sign in if user failed login three times in a row;
- Turn off init animation;

BUG=chromium-os:18532, chromium-os:18668, chromium-os:18312, chromium-os:18307
TEST=Verify fix for chromium-os:18532,chromium-os:18668,chrmoum-os:18312 and chromium-os:18307.

Review URL: http://codereview.chromium.org/7461142

TBR=zelidrag@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=95553