[BREAKING CHANGE] WindowManager: Error if .static.name is not defined when adding a window
[BREAKING CHANGE] WindowManager: Error if .static.name is not defined when adding a window

Also remove broken check above, which is covered by the new one now.

Follow-up to I3cd697cb649255c60d70f0533a371cd8a839f08e.

Bug: T149807
Change-Id: Ie90b0a0590af0b4339bc1e7f48c5dada48dec014

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui