Share code between Navigator and WorkerNavigator

Also shares code between Location and WorkerLocation. This has been done
by introducing NavigatorInfo and UrlHelper.

Fixes #3159

components/script/dom/urlhelper.rs

@@ -0,0 +1,30 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use servo_util::str::DOMString;
+use url::Url;
+
+pub struct UrlHelper;
+
+impl UrlHelper {
+    pub fn Href(url: &Url) -> DOMString {
+        url.serialize()
+    }
+
+    pub fn Search(url: &Url) -> DOMString {
+        match url.query {
+            None => "".to_string(),
+            Some(ref query) if query.as_slice() == "" => "".to_string(),
+            Some(ref query) => "?".to_string().append(query.as_slice())
+        }
+    }
+
+    pub fn Hash(url: &Url) -> DOMString {
+        match url.fragment {
+            None => "".to_string(),
+            Some(ref hash) if hash.as_slice() == "" => "".to_string(),
+            Some(ref hash) => "#".to_string().append(hash.as_slice())
+        }
+    }
+}