Remove CoreResourceMsg::Load.

Also remove now-dead code that rustc warns about.

It turns out that we lost support for some of our custom URL schemes; I intend
to reimplement them, but I believe this will be significantly easier to do
once the legacy code is out of the way.

components/net_traits/lib.rs

@@ -414,8 +414,6 @@ pub struct WebSocketConnectData {
 
 #[derive(Deserialize, Serialize)]
 pub enum CoreResourceMsg {
-    /// Request the data associated with a particular URL
-    Load(LoadData, LoadConsumer, Option<IpcSender<ResourceId>>),
     Fetch(RequestInit, IpcSender<FetchResponseMsg>),
     /// Try to make a websocket connection to a URL.
     WebsocketConnect(WebSocketCommunicate, WebSocketConnectData),