An RFB object represents a single connection so it doesn't make
sense to have one without it trying to connect right away. Matches
the behaviour of other APIs, e.g. WebSocket.
Use normal properties with JavaScript setters and getters instead of
our homegrown stuff.
This also changes the properties to follow normal naming conventions.
The browsers currently do not default to same-origin behaviour for
modules, so we need to be explicit in order for necessary
credentials to be passed along. This seems to be changing though,
but we need to wait for the browsers to actually roll out more
lenient defaults:
https://github.com/whatwg/fetch/pull/585
Pierre Ossman
Frederik Carlier
Samuel Mannehed