servoshell: Move headless setting to ServoShellPreferences (#35377)

This is only used in servoshell, even though it was plumbed through
script previously. It's just about how the `RenderingContext` is set up,
which is something managed entirely outside of servo itself.

In addition, make the name of `servo_shell_preferences` in `app.rs` more
consistent with the rest of the codebase.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/script/dom/dissimilaroriginwindow.rs

@@ -64,7 +64,6 @@ impl DissimilarOriginWindow {
                 // FIXME(nox): The microtask queue is probably not important
                 // here, but this whole DOM interface is a hack anyway.
                 global_to_clone_from.microtask_queue().clone(),
-                global_to_clone_from.is_headless(),
                 global_to_clone_from.get_user_agent(),
                 #[cfg(feature = "webgpu")]
                 global_to_clone_from.wgpu_id_hub(),

components/script/dom/globalscope.rs

@@ -316,9 +316,6 @@ pub(crate) struct GlobalScope {
     #[allow(clippy::vec_box)]
     consumed_rejections: DomRefCell<Vec<Box<Heap<*mut JSObject>>>>,
 
-    /// True if headless mode.
-    is_headless: bool,
-
     /// An optional string allowing the user agent to be set for testing.
     user_agent: Cow<'static, str>,
 
@@ -716,7 +713,6 @@ impl GlobalScope {
         origin: MutableOrigin,
         creation_url: Option<ServoUrl>,
         microtask_queue: Rc<MicrotaskQueue>,
-        is_headless: bool,
         user_agent: Cow<'static, str>,
         #[cfg(feature = "webgpu")] gpu_id_hub: Arc<IdentityHub>,
         inherited_secure_context: Option<bool>,
@@ -751,7 +747,6 @@ impl GlobalScope {
             event_source_tracker: DOMTracker::new(),
             uncaught_rejections: Default::default(),
             consumed_rejections: Default::default(),
-            is_headless,
             user_agent,
             #[cfg(feature = "webgpu")]
             gpu_id_hub,
@@ -2911,10 +2906,6 @@ impl GlobalScope {
         );
     }
 
-    pub(crate) fn is_headless(&self) -> bool {
-        self.is_headless
-    }
-
     pub(crate) fn get_user_agent(&self) -> Cow<'static, str> {
         self.user_agent.clone()
     }

components/script/dom/window.rs

@@ -2778,7 +2778,6 @@ impl Window {
         unminify_css: bool,
         local_script_source: Option<String>,
         userscripts_path: Option<String>,
-        is_headless: bool,
         replace_surrogates: bool,
         user_agent: Cow<'static, str>,
         player_context: WindowGLContext,
@@ -2807,7 +2806,6 @@ impl Window {
                 origin,
                 Some(creator_url),
                 microtask_queue,
-                is_headless,
                 user_agent,
                 #[cfg(feature = "webgpu")]
                 gpu_id_hub,

components/script/dom/workerglobalscope.rs

@@ -79,7 +79,6 @@ pub(crate) fn prepare_workerscope_init(
         pipeline_id: global.pipeline_id(),
         origin: global.origin().immutable().clone(),
         creation_url: global.creation_url().clone(),
-        is_headless: global.is_headless(),
         user_agent: global.get_user_agent(),
         inherited_secure_context: Some(global.is_secure_context()),
     };
@@ -165,7 +164,6 @@ impl WorkerGlobalScope {
                 MutableOrigin::new(init.origin),
                 init.creation_url,
                 runtime.microtask_queue.clone(),
-                init.is_headless,
                 init.user_agent,
                 #[cfg(feature = "webgpu")]
                 gpu_id_hub,

components/script/dom/workletglobalscope.rs

@@ -96,7 +96,6 @@ impl WorkletGlobalScope {
                 MutableOrigin::new(ImmutableOrigin::new_opaque()),
                 None,
                 Default::default(),
-                init.is_headless,
                 init.user_agent.clone(),
                 #[cfg(feature = "webgpu")]
                 init.gpu_id_hub.clone(),
@@ -186,8 +185,6 @@ pub(crate) struct WorkletGlobalScopeInit {
     pub(crate) to_constellation_sender: IpcSender<(PipelineId, ScriptMsg)>,
     /// The image cache
     pub(crate) image_cache: Arc<dyn ImageCache>,
-    /// True if in headless mode
-    pub(crate) is_headless: bool,
     /// An optional string allowing the user agent to be set for testing
     pub(crate) user_agent: Cow<'static, str>,
     /// Identity manager for WebGPU resources