We totally use this

We check to see if the component we're rendering is in
HomepageComponents, and if it isn't we show an 'invalid portlet'
message.

When this comment was added in 6c33588 we really weren't using
allowed_components, but when we started using it in 890312ab the comment
wasn't removed.
Require Symbol::Global::Name 0.02 so the names of references are found

Fixed on 4.0-trunk as 3cb2f29.  Resolves [rt3 #16951] for master.