A VkSurfaceKHR may not have an intrinsic size as is the case on Fuchsia.

This is broken since 718ae508 ("Vulkan: Always query EGL_WIDTH and
EGL_HEIGHT"); queries for EGL_WIDTH or EGL_HEIGHT now always return -1.

Switch back to the old behavior in this case.

Bug: angleproject:4624
Change-Id: I7e7bf569db9aec9890b2cb184056be5a6031bd98
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2191173Reviewed-by: Ian Elliott <ianelliott@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>