These are slightly unfortunate as we're crossing the library boundary,
but there's precedent with Object::is_dom_node(), and these are just
knocking down a few more items that were showing up in profiles.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
Specification: https://dom.spec.whatwg.org/#concept-event-dispatch
This also introduces shadow roots due to it being a requirement of
the event dispatcher.
However, it does not introduce the full shadow DOM, that can be
left for future work.
This changes some event dispatches which require certain attributes
to be initialised to a value.
LibWeb keeps growing and the Web namespace is filling up fast.
Let's put DOM stuff into Web::DOM, just like we already started doing
with SVG stuff in Web::SVG.
We still have to hand-write a function to turn an Event& into a wrapper
but this is still a hue improvement. Eventually we'll find a way to
auto-generate that function as well.
This patch adds the Event base class, along with a MouseEvent subclass.
We now dispatch MouseEvent objects for mousedown, mouseup and mousemove
and these objects have the .offsetX and .offsetY properties.
Both of those properties are hard-coded at the moment. This will be
fixed in the next patch. :^)
