Bug 1094550 - Unable to create a new account because Year of Birth …
dropdown doesn't work.

 - Create a value selector overlay to listen to the event for showing
   value selector for trusted UI.
 - Let trusted UI module init its own value selector controller.

 r=alive.
Merge pull request #26357 from RudyLu/keyboard/Bug1094550_uplift_v2.1

Bug 1094550 - Unable to create a new account because Year of Birth … dropdown
r=alive.