clippy: Fix last few warnings (#32270)

* Fix clippy in components/script

warning: writing `&mut Vec` instead of `&mut [_]` involves a new object where a slice will do (components/script/dom/htmlformelement.rs:896:20)

warning: `Box::new(_)` of default value (components/script/dom/paintworkletglobalscope.rs:291:29)

warning: this creates an owned instance just for comparison (components/script/dom/radionodelist.rs:105:50)

* Fix clippy in layout_thread (2013 and 2020)

warning: this `if` statement can be collapsed (components/layout_thread/lib.rs:876:17)

warning: the following explicit lifetimes could be elided: 'a (components/layout_thread/lib.rs:239 and 2020 same line)

warning: deref which would be done by auto-deref (components/layout_thread/lib.rs:500 and 1289)

warning: dereferencing a tuple pattern where every element takes a reference (components/layout_thread/lib.rs:503,1562 and 2020 line 1153)

warning: useless conversion to the same type: `style::invalidation::element::restyle_hints::RestyleHint` (components/layout_thread_2020/lib.rs:742:36)

* Fix clippy in components/servo

warning: constants have by default a `'static` lifetime (components/servo/lib.rs:1238:31)

warning: creating a `let` binding to a value of unit type, which usually
can't be used afterwards (5 occurances in components/servo/lib.rs)

* FIx clippy in ports/servoshell

warning: this expression creates a reference which is immediately dereferenced by the compiler (ports/servoshell/app.rs:251:89)

warning: using `clone` on type `Option<TopLevelBrowsingContextId>` which implements the `Copy` trait (ports/servoshell/webview.rs:122:9)

components/layout_thread/lib.rs

@@ -260,7 +260,7 @@ impl Layout for LayoutThread {
         self.handle_request(Request::FromFontCache);
     }
 
-    fn device<'a>(&'a self) -> &'a Device {
+    fn device(&self) -> &Device {
         self.stylist.device()
     }
 
@@ -497,10 +497,10 @@ impl Layout for LayoutThread {
         let properties = properties
             .drain(..)
             .filter_map(|name| {
-                let id = PropertyId::parse_enabled_for_all_content(&*name).ok()?;
+                let id = PropertyId::parse_enabled_for_all_content(&name).ok()?;
                 Some((name.clone(), id))
             })
-            .filter(|&(_, ref id)| !id.is_shorthand())
+            .filter(|(_, id)| !id.is_shorthand())
             .collect();
         let registered_painter = RegisteredPainterImpl {
             name: name.clone(),
@@ -873,40 +873,39 @@ impl LayoutThread {
                 let traversal = ComputeStackingRelativePositions { layout_context };
                 traversal.traverse(layout_root);
 
-                if layout_root
+                if (layout_root
                     .base()
                     .restyle_damage
                     .contains(ServoRestyleDamage::REPAINT) ||
-                    self.display_list.borrow().is_none()
+                    self.display_list.borrow().is_none()) &&
+                    reflow_goal.needs_display_list()
                 {
-                    if reflow_goal.needs_display_list() {
-                        let background_color = get_root_flow_background_color(layout_root);
-                        let mut build_state = sequential::build_display_list_for_subtree(
-                            layout_root,
-                            layout_context,
-                            background_color,
-                            data.page_clip_rect.size,
-                        );
-
-                        debug!("Done building display list.");
-
-                        let root_size = {
-                            let root_flow = layout_root.base();
-                            root_flow.overflow.scroll.size
-                        };
-
-                        let origin = Rect::new(Point2D::new(Au(0), Au(0)), root_size).to_layout();
-                        build_state.root_stacking_context.bounds = origin;
-                        build_state.root_stacking_context.overflow = origin;
-
-                        // We will not use build_state.iframe_sizes again, so it's safe to move it.
-                        let iframe_sizes = std::mem::take(&mut build_state.iframe_sizes);
-                        self.update_iframe_sizes(iframe_sizes);
-
-                        *self.indexable_text.borrow_mut() =
-                            std::mem::take(&mut build_state.indexable_text);
-                        *self.display_list.borrow_mut() = Some(build_state.to_display_list());
-                    }
+                    let background_color = get_root_flow_background_color(layout_root);
+                    let mut build_state = sequential::build_display_list_for_subtree(
+                        layout_root,
+                        layout_context,
+                        background_color,
+                        data.page_clip_rect.size,
+                    );
+
+                    debug!("Done building display list.");
+
+                    let root_size = {
+                        let root_flow = layout_root.base();
+                        root_flow.overflow.scroll.size
+                    };
+
+                    let origin = Rect::new(Point2D::new(Au(0), Au(0)), root_size).to_layout();
+                    build_state.root_stacking_context.bounds = origin;
+                    build_state.root_stacking_context.overflow = origin;
+
+                    // We will not use build_state.iframe_sizes again, so it's safe to move it.
+                    let iframe_sizes = std::mem::take(&mut build_state.iframe_sizes);
+                    self.update_iframe_sizes(iframe_sizes);
+
+                    *self.indexable_text.borrow_mut() =
+                        std::mem::take(&mut build_state.indexable_text);
+                    *self.display_list.borrow_mut() = Some(build_state.to_display_list());
                 }
 
                 if !reflow_goal.needs_display() {
@@ -1286,7 +1285,7 @@ impl LayoutThread {
         thread_pool: Option<&rayon::ThreadPool>,
     ) {
         Self::cancel_animations_for_nodes_not_in_flow_tree(
-            &mut *(context.style_context.animations.sets.write()),
+            &mut (context.style_context.animations.sets.write()),
             FlowRef::deref_mut(root_flow),
         );
 
@@ -1559,7 +1558,7 @@ fn get_ua_stylesheets() -> Result<UserAgentStylesheets, &'static str> {
         )?,
     ];
 
-    for &(ref contents, ref url) in &opts::get().user_stylesheets {
+    for (contents, url) in &opts::get().user_stylesheets {
         user_or_user_agent_stylesheets.push(DocumentStyleSheet(ServoArc::new(
             Stylesheet::from_bytes(
                 contents,

components/layout_thread_2020/lib.rs

@@ -236,7 +236,7 @@ impl Layout for LayoutThread {
         self.handle_request(Request::FromFontCache);
     }
 
-    fn device<'a>(&'a self) -> &'a Device {
+    fn device(&self) -> &Device {
         self.stylist.device()
     }
 
@@ -739,7 +739,7 @@ impl LayoutThread {
             }
 
             // Stash the data on the element for processing by the style system.
-            style_data.hint.insert(restyle.hint.into());
+            style_data.hint.insert(restyle.hint);
             style_data.damage = restyle.damage;
             debug!("Noting restyle for {:?}: {:?}", el, style_data);
         }
@@ -1150,7 +1150,7 @@ fn get_ua_stylesheets() -> Result<UserAgentStylesheets, &'static str> {
         )?,
     ];
 
-    for &(ref contents, ref url) in &opts::get().user_stylesheets {
+    for (contents, url) in &opts::get().user_stylesheets {
         user_or_user_agent_stylesheets.push(DocumentStyleSheet(ServoArc::new(
             Stylesheet::from_bytes(
                 contents,

components/script/dom/htmlformelement.rs

@@ -893,7 +893,7 @@ impl HTMLFormElement {
     // https://html.spec.whatwg.org/multipage/#submit-body
     fn submit_entity_body(
         &self,
-        form_data: &mut Vec<FormDatum>,
+        form_data: &mut [FormDatum],
         mut load_data: LoadData,
         enctype: FormEncType,
         encoding: &'static Encoding,

components/script/dom/paintworkletglobalscope.rs

@@ -15,7 +15,7 @@ use dom_struct::dom_struct;
 use euclid::{Scale, Size2D};
 use js::jsapi::{
     HandleValueArray, Heap, IsCallable, IsConstructor, JSAutoRealm, JSObject,
-    JS_ClearPendingException, JS_IsExceptionPending, NewArrayObject,
+    JS_ClearPendingException, JS_IsExceptionPending, NewArrayObject, Value,
 };
 use js::jsval::{JSVal, ObjectValue, UndefinedValue};
 use js::rust::wrappers::{Call, Construct1};
@@ -288,7 +288,7 @@ impl PaintWorkletGlobalScope {
                 }
                 // Step 5.4
                 entry
-                    .insert(Box::new(Heap::default()))
+                    .insert(Box::<Heap<Value>>::default())
                     .set(paint_instance.get());
             },
         };

components/script/dom/radionodelist.rs

@@ -102,7 +102,7 @@ impl RadioNodeListMethods for RadioNodeList {
             // Step 1
             if let Some(input) = node.downcast::<HTMLInputElement>() {
                 match input.input_type() {
-                    InputType::Radio if value == DOMString::from("on") => {
+                    InputType::Radio if value == *"on" => {
                         // Step 2
                         let val = input.Value();
                         if val.is_empty() || val == value {

components/servo/lib.rs

@@ -1059,8 +1059,7 @@ impl gfx_traits::WebrenderApi for FontCacheWR {
         flags: FontInstanceFlags,
     ) -> FontInstanceKey {
         let (sender, receiver) = unbounded();
-        let _ = self
-            .0
+        self.0
             .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Font(
                 FontToCompositorMsg::AddFontInstance(font_key, size, flags, sender),
             )));
@@ -1070,8 +1069,7 @@ impl gfx_traits::WebrenderApi for FontCacheWR {
         let (sender, receiver) = unbounded();
         let (bytes_sender, bytes_receiver) =
             ipc::bytes_channel().expect("failed to create IPC channel");
-        let _ = self
-            .0
+        self.0
             .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Font(
                 FontToCompositorMsg::AddFont(sender, index, bytes_receiver),
             )));
@@ -1081,8 +1079,7 @@ impl gfx_traits::WebrenderApi for FontCacheWR {
 
     fn add_system_font(&self, handle: NativeFontHandle) -> FontKey {
         let (sender, receiver) = unbounded();
-        let _ = self
-            .0
+        self.0
             .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Font(
                 FontToCompositorMsg::AddSystemFont(sender, handle),
             )));
@@ -1096,16 +1093,14 @@ struct CanvasWebrenderApi(CompositorProxy);
 impl canvas_paint_thread::WebrenderApi for CanvasWebrenderApi {
     fn generate_key(&self) -> Option<ImageKey> {
         let (sender, receiver) = unbounded();
-        let _ = self
-            .0
+        self.0
             .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Canvas(
                 CanvasToCompositorMsg::GenerateKey(sender),
             )));
         receiver.recv().ok()
     }
     fn update_images(&self, updates: Vec<canvas_paint_thread::ImageUpdate>) {
-        let _ = self
-            .0
+        self.0
             .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Canvas(
                 CanvasToCompositorMsg::UpdateImages(updates),
             )));
@@ -1235,29 +1230,29 @@ enum UserAgent {
 
 fn default_user_agent_string_for(agent: UserAgent) -> &'static str {
     #[cfg(all(target_os = "linux", target_arch = "x86_64", not(target_env = "ohos")))]
-    const DESKTOP_UA_STRING: &'static str =
+    const DESKTOP_UA_STRING: &str =
         "Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Servo/1.0 Firefox/111.0";
     #[cfg(all(
         target_os = "linux",
         not(target_arch = "x86_64"),
         not(target_env = "ohos")
     ))]
-    const DESKTOP_UA_STRING: &'static str =
+    const DESKTOP_UA_STRING: &str =
         "Mozilla/5.0 (X11; Linux i686; rv:109.0) Servo/1.0 Firefox/111.0";
 
     #[cfg(all(target_os = "windows", target_arch = "x86_64"))]
-    const DESKTOP_UA_STRING: &'static str =
+    const DESKTOP_UA_STRING: &str =
         "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Servo/1.0 Firefox/111.0";
     #[cfg(all(target_os = "windows", not(target_arch = "x86_64")))]
-    const DESKTOP_UA_STRING: &'static str =
+    const DESKTOP_UA_STRING: &str =
         "Mozilla/5.0 (Windows NT 10.0; rv:109.0) Servo/1.0 Firefox/111.0";
 
     #[cfg(target_os = "macos")]
-    const DESKTOP_UA_STRING: &'static str =
+    const DESKTOP_UA_STRING: &str =
         "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Servo/1.0 Firefox/111.0";
 
     #[cfg(any(target_os = "android", target_env = "ohos"))]
-    const DESKTOP_UA_STRING: &'static str = "";
+    const DESKTOP_UA_STRING: &str = "";
 
     match agent {
         UserAgent::Desktop => DESKTOP_UA_STRING,

ports/servoshell/app.rs

@@ -248,7 +248,7 @@ impl App {
                         window_id: _,
                     } => {
                         let response =
-                            minibrowser.on_window_event(window.winit_window().unwrap(), &event);
+                            minibrowser.on_window_event(window.winit_window().unwrap(), event);
                         // Update minibrowser if there's resize event to sync up with window.
                         if let WindowEvent::Resized(_) = event {
                             minibrowser.update(

ports/servoshell/webview.rs

@@ -119,7 +119,7 @@ where
     }
 
     pub fn focused_webview_id(&self) -> Option<WebViewId> {
-        self.focused_webview_id.clone()
+        self.focused_webview_id
     }
 
     pub fn current_url_string(&self) -> Option<&str> {