Don't double-terminate a display. Some dEQP tests call eglTerminate twice on the same display and cause crashes. BUG=angleproject:2546 Change-Id: I8a13d00fd03692b3b24dee4813c245d83ea00862 Reviewed-on: https://chromium-review.googlesource.com/1060335 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>