Fix MetalWindowContext setup.

Previous changes fixed the zombie device and queue, assuming that
they're bridged correctly.

Bug: skia:8243
Change-Id: Id4c2d10beacbb2ac749187d8d54fc2d276cf7b3d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/219378
Auto-Submit: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed