Added Websocket to RequestMode enum

set unreachable in dom/request.rs for websocket

fixed imports

components/net/resource_thread.rs

@@ -330,6 +330,7 @@ impl CoreResourceManager {
         let ua = self.user_agent.clone();
         let dc = self.devtools_chan.clone();
         let filemanager = self.filemanager.clone();
+
         thread::Builder::new().name(format!("fetch thread for {}", init.url)).spawn(move || {
             let request = Request::from_init(init);
             // XXXManishearth: Check origin against pipeline id (also ensure that the mode is allowed)

components/net_traits/request.rs

@@ -77,6 +77,7 @@ pub enum RequestMode {
     SameOrigin,
     NoCors,
     CorsMode,
+    WebSocket
 }
 
 /// Request [credentials mode](https://fetch.spec.whatwg.org/#concept-request-credentials-mode)

components/script/dom/request.rs

@@ -826,6 +826,7 @@ impl Into<RequestMode> for NetTraitsRequestMode {
             NetTraitsRequestMode::SameOrigin => RequestMode::Same_origin,
             NetTraitsRequestMode::NoCors => RequestMode::No_cors,
             NetTraitsRequestMode::CorsMode => RequestMode::Cors,
+            NetTraitsRequestMode::WebSocket => unreachable!("Websocket request mode should never be exposed to JS"),
         }
     }
 }