set referrer in window.load_url

- this conforms to follow-hyperlinks spec step 13
- this conforms to window-open spec step 14.3
- replace uses of `referrer_url` with `referrer`
- in Request class, change "no-referrer" to ""
- set websocket fetch referrer to "no-referrer"

components/script/dom/serviceworkerglobalscope.rs

@@ -30,7 +30,7 @@ use ipc_channel::router::ROUTER;
 use js::jsapi::{JSAutoCompartment, JSContext, JS_AddInterruptCallback};
 use js::jsval::UndefinedValue;
 use msg::constellation_msg::PipelineId;
-use net_traits::request::{CredentialsMode, Destination, RequestBuilder};
+use net_traits::request::{CredentialsMode, Destination, Referrer, RequestBuilder};
 use net_traits::{load_whole_resource, CustomResponseMediator, IpcSend};
 use script_traits::{
     ScopeThings, ServiceWorkerMsg, TimerEvent, WorkerGlobalScopeInit, WorkerScriptLoadOrigin,
@@ -281,12 +281,14 @@ impl ServiceWorkerGlobalScope {
                     pipeline_id,
                 } = worker_load_origin;
 
+                let referrer = referrer_url.map(|referrer_url| Referrer::ReferrerUrl(referrer_url));
+
                 let request = RequestBuilder::new(script_url.clone())
                     .destination(Destination::ServiceWorker)
                     .credentials_mode(CredentialsMode::Include)
                     .use_url_credentials(true)
                     .pipeline_id(pipeline_id)
-                    .referrer_url(referrer_url)
+                    .referrer(referrer)
                     .referrer_policy(referrer_policy)
                     .origin(origin);