This new code generator takes all the .idl files in LibWeb, looks for
each top level interface in there with an [Exposed=Foo] attribute, and
adds code to add the constructor and prototype for each of those exposed
interfaces to the realm of the relevant global object we're initialzing.
It will soon replace WindowObjectHelper as the way that web interfaces
are added to the Window object, and will be used in the future for
creating proper WorkerGlobalScope objects for dedicated and shared
workers.
