Instead of each IDL interface wrapper having its own set of all the
attributes and functions, they are moved to the prototype. This matches
what we already do in LibJS.
Also, this should be spec compliant with the web as well, though there
may be *some* content out there that expects some things to be directly
on the wrapper since that's how things used to work in major browsers
a long time ago. But let's just not worry about that for now.
More work towards #4789
We now instantiate all the generated web API constructors and expose
them on the window object. We also set the generated prototypes on
instantiated wrappers.
Also, we should obviously find a way to generate this code. :^)
