This make sure the VkFormat/internalformat combinations that Chrome uses
succeed import, which in particular requires the object size to match.

Allowing VK_FORMAT_R8G8B8_UNORM VkFormat for GL_RGB8 will make this test
fail when run on a native vulkan that supports that format.

Bug: chromium:1058521
Change-Id: I91483568ba8552f40314f10215bfea59e5ca2b94
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2088652
Commit-Queue: Michael Spang <spang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>