pledge_domains() that takes only one String argument was specifically
added as a shortcut for pledging a single domain. So, it makes sense to
use singular here.
In order to propagate errors that occur during UI setup, we have to move
all that logic out of widget/window subclass constructors. This is a
first attempt at doing that, for GUI::SettingsWindow.
Browser has a bunch of settings, but most are non-trivial to add here.
So far, these are implemented:
- Homepage URL
- Whether to close download windows when they complete
The others will be added in subsequent commits.
