Don't call Texture::onDestroy twice for the zero textures. The BindingPointer will call onDestroy when all references are removed, no need to do it explicitly. BUG=angleproject:3070 Change-Id: Ic5dd4da8f73e204d26d9d3a3c6e1eff9fded5411 Reviewed-on: https://chromium-review.googlesource.com/c/1409868 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>