Vector sprites appear jagged after exiting full-screen mode

[adroitwhiz]

Expected Behavior

Vector sprites should never appear jagged.

Actual Behavior

Vector sprites appear jagged if you enter full-screen mode then exit it:

Before full-screen	After full-screen

This is because of Drawable.useNearest. #480 changed useNearest to take stage scale into account, but there's one missing variable still: the skin's dimensions.

In normal-stage mode, useNearest enables nearest-neighbor sampling because the drawable's screen-space scale is 100%. It doesn't ensure that one screen-space pixel is roughly the same size as one skin-texture pixel, assuming it to always be true. Entering full-screen mode causes the SVG skin to re-rasterize at a higher resolution, breaking this assumption.

Steps to Reproduce

1. Create a new project
2. Enter full-screen mode
3. Exit full-screen mode

[fsih]

We noticed this too and felt it should be ok until #431 goes in

[fsih]

/cc @paulkaplan @cwillisf