Vulkan: Never stage update for EGLImage EGLImage could be shared between contexts in different share groups. If we stage any update in the ImageHelper for such EGLImage, then you may run into threading bugs when two textures are trying to flush out the staged update at the same time. There is no evidence showing we are running into this issue, but this CL forces this requirement. Bug: b/169868803 Change-Id: Ie26542225705ee4638ca1b3cf3cc5af499685137 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3824159 Reviewed-by: Ian Elliott <ianelliott@google.com> Commit-Queue: Charlie Lao <cclao@google.com> Reviewed-by: Geoff Lang <geofflang@chromium.org>