Vulkan: fix uint indices causing incomplete buffer Fixes buffer size calculation when uploading element buffer to account for 4-byte (uint) indices. Bug: angleproject:2902 Change-Id: Id70fc0fdffecd0b27995820bd0ad88e4cb61e013 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1648325 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>