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/htmlanchorelement.rs

@@ -27,6 +27,7 @@ use crate::dom::urlhelper::UrlHelper;
 use crate::dom::virtualmethods::VirtualMethods;
 use dom_struct::dom_struct;
 use html5ever::{LocalName, Prefix};
+use net_traits::request::Referrer;
 use num_traits::ToPrimitive;
 use servo_url::ServoUrl;
 use std::default::Default;
@@ -639,7 +640,7 @@ pub fn follow_hyperlink(subject: &Element, hyperlink_suffix: Option<String>) {
         // will have been done as part of Step 7 above
         // in choose_browsing_context/create_auxiliary_browsing_context.
 
-        // Step 10, 11, 12, 13. TODO: if parsing the URL failed, navigate to error page.
+        // Step 10, 11. TODO: if parsing the URL failed, navigate to error page.
         let attribute = subject.get_attribute(&ns!(), &local_name!("href")).unwrap();
         let mut href = attribute.Value();
         // Step 11: append a hyperlink suffix.
@@ -657,8 +658,16 @@ pub fn follow_hyperlink(subject: &Element, hyperlink_suffix: Option<String>) {
             .get_attribute_by_name(DOMString::from_string(String::from("referrerpolicy")))
             .and_then(|attribute: DomRoot<Attr>| (determine_policy_for_token(&attribute.Value())));
 
-        // Step 13, 14.
+        // Step 13
+        let referrer = match subject.get_attribute(&ns!(), &local_name!("rel")) {
+            Some(ref link_types) if link_types.Value().contains("noreferrer") => {
+                Referrer::NoReferrer
+            },
+            _ => Referrer::Client,
+        };
+
+        // Step 14
         debug!("following hyperlink to {}", url);
-        target_window.load_url(url, replace, false, referrer_policy);
+        target_window.load_url(url, replace, false, referrer, referrer_policy);
     };
 }