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/navigatorinfo.rs

@@ -0,0 +1,29 @@
+/* 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;
+
+pub struct NavigatorInfo;
+
+impl NavigatorInfo {
+    pub fn Product() -> DOMString {
+        "Gecko".to_string()
+    }
+
+    pub fn TaintEnabled() -> bool {
+        false
+    }
+
+    pub fn AppName() -> DOMString {
+        "Netscape".to_string() // Like Gecko/Webkit
+    }
+
+    pub fn AppCodeName() -> DOMString {
+        "Mozilla".to_string()
+    }
+
+    pub fn Platform() -> DOMString {
+        "".to_string()
+    }
+}