Window.h is a rather heavy file, so let's try not to include it in
header files when we can!
Element.h now also includes LibWeb/Bindings/Intrinsics.h, but that's
just out of my laziness. Most if not all objects call
`Bindings::ensure_web_prototype<>()` anyway, so I don't think we would
gain much by sticking the header to source files instead.
The potentially scroll/focus and finish AOs are called by the inner
navigate event firing algorithm. Implement them beforehand to make the
diff look pretty :^).
Every property in an IDL dictionary is implied to be optional, unless it
is marked as required. If a dictionary is passed to a method with
optional, but it has at least one required or defaulted member, the
bindings will skip the optionality of the parameter and always pass a
struct with the required parameters filled in.
This event is the star of the show, and the main way that web content
can react to either programmatic or user-initiated navigation.
All of the fun algorithms will have to come later though.
