The stage alignment settings viewport_scale_factor should *not* be
applied to `Stage.transform.matrix`, which is only ever changed
as a result of explicit modification from ActionScript. Instead,
alignment and scaling are performed a separate step, which is
transparent to ActionScript.
I've implemented this through a new `viewport_matrix` field,
which is used during stage rendering and mouse coordinate
transformation.
This makes Stage3D instances properly scale - previously, they
would render unscaled. The linux standalone Flash Player doesn't
seem to use HiDPI mode, so I didn't realize that this was a bug
until now.
In the process of implementing this, I discovered and fixed a bug
with how we handle changing the viewport size under winit.
Calling `self.window.set_inner_size` does not immediately take
effect (at least on X11) - calling `self.window.inner_size()`
will report the old size until the next resize event.
Since build our Stage matrices from `self.window.inner_size()`
(and start running the SWF) immediately after `RuffleEvent::OnMetadata`,
we would run a few SWF frames with an incorrect viewport size. This
is visible to SWFs that have the scale mode set to "noScale", and
could break SWFs that expect the initial viewport size to be
the movie size. I've fixed this by delaying SWF execution until
we get a Resize event (if `self.window.inner_size()` does not
immediately report the size we set).
66aad3ebc5