Scenic places our window in with its center in the corner if we don't
apply any translation. Therefore we only see 1/4 of the surface.

Translate the surface so the full size is visible. Also account for
display scaling as we're sizing in pixels and scenic is sizing in
density independent pixels.

Bug: angleproject:4382
Test: angle_end2end_tests
Change-Id: I1ae0b877c0ed7cf9d810bb2c8317b9842bd322a1
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1716226
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>