* A PageView is a view onto a Page object.
* A Page always has a main Frame (root of Frame tree.)
* Page has a PageClient. PageView is a PageClient.
The goal here is to allow building another kind of view onto
a Page while keeping the rest of LibWeb intact.
Now that PageView actually respects the invalidation rect provided by
the layout system, it turns out we were invalidating too little.
Unfortunately, this is not really fixable until the initial containing
block starts having the right size (same as viewport), but that will
require a bunch of work to make overflow work again. So it's a FIXME
for now, and we'll return to this.
When a paint invalidation occurs inside a subframe, it bubbles up to
Frame::set_needs_display(). From there, we call PageView if this is
the main frame, or otherwise invalidate the subframe host element.
You can still run the old parser with "br -O", but the new one is good
enough to be the default parser now. We'll fix issues as we go and
eventually remove the old one completely. :^)
