Having the text cursor disappear during rapid continuous editing is
quite jarring, so let's make sure we always restart the blink cycle
whenever the user performs some kind of editing action in a frame.
Layout was using an outdated viewport rect that we set *after* doing
a layout due to resize. That meant that layout-in-response-to-resize
was always lagging behind the current size of the view.
The root of this problem was how Frame kept both a viewport rect
(with both scroll offset and size) and a frame size. To fix this,
only store the viewport scroll offset, and always use the frame size.
This way they can't get out of sync and the problem goes away. :^)
Fixes#4250.
This patch makes Page weakable and allows page-less frames to exist.
Page is single-owner, and Frame is multiple-owner, so it's not sound
for Frame to assume its containing Page will stick around for its own
entire lifetime.
Fixes#3976.
This works everywhere right now, but it's obviously not going to stay
that way forever. :^)
Note that this does not advance the cursor correctly for whitespace
since the cursor is DOM-based and doesn't take whitespace collapsing
into account yet.
Each Web::Frame now has a cursor that sits at a DOM::Position. It will
blink and look like a nice regular text cursor.
It doesn't really do anything yet, but it will eventually.
