removes the native-client feature. since using the wasm client requires explicitly specifying a feature for that, the notion of "native-client" isn't relevant anymore. it existed as a magical "no features needed, works across platforms."
loads no default features on http-client. without this, surf does not build on wasm. otherwise we build "wasm and also the default features," which currently means h1-client with tls, which won't build on wasm.
this pr does three things: