SilverStripe 4 vendormodule types make use of an 'expose' composer
directive to allow assets they provide to be accessed by a web request.
Previously the javascript for the iFrame resizing business tried to load
from a static path that no longer exists (referenced inside PHP), which
caused a fatal error. This has been fixed along with making the
conditional code for enforcing a protocol on the page's request a bit more
readable & easily digestable to developers.
