COMMON: Minor whitespace fix.
COMMON: Fix crash when quitting on "Game data not found" dialog

ScummVM would try to look up "confirm_exit" in the active domain,
even though the active domain had been removed and pointed to an
invalid address. To avoid this, try to keep _activeDomain and
_activeDomainName updated if removeGameDomain() removes the active
domain.

For good measure, also do it if the active domain is removed by
renameGameDomain(), though I don't know if there was any case where
this would have caused trouble.