content/dom: set navigator.onLine attribute to true (#36560)

Sets the navigator.onLine attribute to true.

Testing:
Ran `./mach run https://pinterest.com
--enable-experimental-web-platform-features`. This doesn't show the
"Hmm..you're not connected to the internet" text anymore.
<img width="1027" alt="Screenshot 2025-04-16 at 11 31 02 AM"
src="https://github.com/user-attachments/assets/3745077b-dc51-42ce-88a0-38d5f157fc0c"
/>


part of: #36554

---------

Signed-off-by: Siddhant N. Trivedi <sidntrivedi012@gmail.com>
Signed-off-by: Siddhant N Trivedi <sidntrivedi012@gmail.com>
Co-authored-by: Josh Matthews <josh@joshmatthews.net>

components/script/dom/navigator.rs

@@ -222,6 +222,11 @@ impl NavigatorMethods<crate::DomTypeHolder> for Navigator {
         to_frozen_array(&[self.Language()], cx, retval, can_gc)
     }
 
+    /// <https://html.spec.whatwg.org/multipage/#dom-navigator-online>
+    fn OnLine(&self) -> bool {
+        true
+    }
+
     // https://html.spec.whatwg.org/multipage/#dom-navigator-plugins
     fn Plugins(&self) -> DomRoot<PluginArray> {
         self.plugins

components/script/dom/workernavigator.rs

@@ -105,6 +105,11 @@ impl WorkerNavigatorMethods<crate::DomTypeHolder> for WorkerNavigator {
         to_frozen_array(&[self.Language()], cx, retval, can_gc)
     }
 
+    /// <https://html.spec.whatwg.org/multipage/#dom-navigator-online>
+    fn OnLine(&self) -> bool {
+        true
+    }
+
     // https://w3c.github.io/permissions/#navigator-and-workernavigator-extension
     fn Permissions(&self) -> DomRoot<Permissions> {
         self.permissions

components/script_bindings/webidls/Navigator.webidl

@@ -9,7 +9,7 @@ interface Navigator {
 };
 Navigator includes NavigatorID;
 Navigator includes NavigatorLanguage;
-//Navigator includes NavigatorOnLine;
+Navigator includes NavigatorOnLine;
 //Navigator includes NavigatorContentUtils;
 //Navigator includes NavigatorStorageUtils;
 Navigator includes NavigatorPlugins;
@@ -43,6 +43,12 @@ interface mixin NavigatorLanguage {
   readonly attribute any languages;
 };
 
+// https://html.spec.whatwg.org/multipage/#dom-navigator-online
+[Exposed=(Window,Worker)]
+interface mixin NavigatorOnLine {
+  readonly attribute boolean onLine;
+};
+
 // https://html.spec.whatwg.org/multipage/#navigatorplugins
 interface mixin NavigatorPlugins {
   [SameObject] readonly attribute PluginArray plugins;

components/script_bindings/webidls/WorkerNavigator.webidl

@@ -7,7 +7,7 @@
 interface WorkerNavigator {};
 WorkerNavigator includes NavigatorID;
 WorkerNavigator includes NavigatorLanguage;
-//WorkerNavigator includes NavigatorOnLine;
+WorkerNavigator includes NavigatorOnLine;
 WorkerNavigator includes NavigatorConcurrentHardware;
 
 // https://w3c.github.io/permissions/#navigator-and-workernavigator-extension

tests/wpt/meta/html/browsers/offline/browser-state/navigator_online_online.https.html.ini

@@ -1,3 +0,0 @@
-[navigator_online_online.https.html]
-  [Offline Application Cache - navigator_online_online]
-    expected: FAIL

tests/wpt/meta/html/dom/idlharness.any.js.ini

@@ -185,15 +185,9 @@
   [WorkerNavigator interface: member taintEnabled]
     expected: FAIL
 
-  [WorkerNavigator interface: attribute onLine]
-    expected: FAIL
-
   [WorkerNavigator interface: self.navigator must not have property "taintEnabled"]
     expected: FAIL
 
-  [WorkerNavigator interface: self.navigator must inherit property "onLine" with the proper type]
-    expected: FAIL
-
   [OffscreenCanvasRenderingContext2D interface: operation getContextAttributes()]
     expected: FAIL
 

tests/wpt/meta/html/dom/idlharness.https.html.ini

@@ -695,9 +695,6 @@
   [CanvasRenderingContext2D interface: document.createElement("canvas").getContext("2d") must inherit property "imageSmoothingQuality" with the proper type]
     expected: FAIL
 
-  [Navigator interface: attribute onLine]
-    expected: FAIL
-
   [OffscreenCanvasRenderingContext2D interface: operation getLineDash()]
     expected: FAIL
 
@@ -5348,9 +5345,6 @@
   [Navigator interface: attribute oscpu]
     expected: FAIL
 
-  [Navigator interface: attribute onLine]
-    expected: FAIL
-
   [Navigator interface: operation registerProtocolHandler(DOMString, USVString)]
     expected: FAIL
 
@@ -5366,9 +5360,6 @@
   [Navigator interface: window.navigator must inherit property "oscpu" with the proper type]
     expected: FAIL
 
-  [Navigator interface: window.navigator must inherit property "onLine" with the proper type]
-    expected: FAIL
-
   [Navigator interface: window.navigator must inherit property "registerProtocolHandler(DOMString, USVString)" with the proper type]
     expected: FAIL
 

tests/wpt/meta/workers/WorkerNavigator.any.js.ini

@@ -3,7 +3,3 @@
 
 [WorkerNavigator.any.serviceworker.html]
   expected: ERROR
-
-[WorkerNavigator.any.worker.html]
-  [Testing Navigator properties on workers.]
-    expected: FAIL