On Mac, blitFramebuffer calls fail if the source region is not enclosed
by the framebuffer. In this case, we must naively clip the source region
and adjust the dest region accordingly. This is slightly different
behavior and may cause issues with scaling so we use a separate
workaround.

Also, Windows NVIDIA has a driver bug that affects Vulkan device
creation after blitting large textures, so it should be included in the
original workaround.

This CL cleans up the workaround to use more helpers from ANGLE and to
generally improve readability.

Bug: chromium:830046
Change-Id: I50bd97449725b738036e6bd3af82362020d7eda8
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1713090
Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>