clippy: fix several lint warns (#32126)

As seems #31500 still remain opened here's the next partial fix.

Fixed list: `unused_mut`, `clippy::needless_borrow`,
`clippy::match_ref_pats`, `clippy::borrow_deref_ref`, `clippy::ptr_eq`,
`clippy::unnecessary_cast`, `clippy::derivable_impls`,
`clippy::collapsible_match`, `clippy::extra_unused_lifetimes`,
`clippy::map_clone`, `clippy::manual_filter`.


- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes are part of #31500.
- [x] These changes do not require tests because are only cosmetic.

components/layout_thread_2020/lib.rs

@@ -555,7 +555,7 @@ impl LayoutThread {
     }
 
     /// Receives and dispatches messages from the script and constellation threads
-    fn handle_request<'a, 'b>(&mut self, request: Request) {
+    fn handle_request(&mut self, request: Request) {
         match request {
             Request::FromPipeline(LayoutControlMsg::SetScrollStates(new_scroll_states)) => {
                 self.handle_request_helper(Msg::SetScrollStates(new_scroll_states))
@@ -629,13 +629,13 @@ impl LayoutThread {
     ) {
         // Find all font-face rules and notify the font cache of them.
         // GWTODO: Need to handle unloading web fonts.
-        if stylesheet.is_effective_for_device(self.stylist.device(), &guard) {
+        if stylesheet.is_effective_for_device(self.stylist.device(), guard) {
             let newly_loading_font_count = self
                 .font_cache_thread
                 .lock()
                 .add_all_web_fonts_from_stylesheet(
-                    &*stylesheet,
-                    &guard,
+                    stylesheet,
+                    guard,
                     self.stylist.device(),
                     &self.font_cache_sender,
                     self.debug.load_webfonts_synchronously,
@@ -658,7 +658,7 @@ impl LayoutThread {
     }
 
     /// Sets quirks mode for the document, causing the quirks mode stylesheet to be used.
-    fn handle_set_quirks_mode<'a, 'b>(&mut self, quirks_mode: QuirksMode) {
+    fn handle_set_quirks_mode(&mut self, quirks_mode: QuirksMode) {
         self.stylist.set_quirks_mode(quirks_mode);
     }
 
@@ -1048,7 +1048,7 @@ impl LayoutThread {
             .borrow()
             .iter()
             .filter_map(|(browsing_context_id, size)| {
-                match old_iframe_sizes.get(&browsing_context_id) {
+                match old_iframe_sizes.get(browsing_context_id) {
                     Some(old_size) if old_size != size => Some(IFrameSizeMsg {
                         browsing_context_id: *browsing_context_id,
                         size: *size,
@@ -1145,17 +1145,17 @@ fn get_ua_stylesheets() -> Result<UserAgentStylesheets, &'static str> {
     //        (Does it make a difference?)
     let mut user_or_user_agent_stylesheets = vec![
         parse_ua_stylesheet(
-            &shared_lock,
+            shared_lock,
             "user-agent.css",
             &resources::read_bytes(Resource::UserAgentCSS),
         )?,
         parse_ua_stylesheet(
-            &shared_lock,
+            shared_lock,
             "servo.css",
             &resources::read_bytes(Resource::ServoCSS),
         )?,
         parse_ua_stylesheet(
-            &shared_lock,
+            shared_lock,
             "presentational-hints.css",
             &resources::read_bytes(Resource::PresentationalHintsCSS),
         )?,
@@ -1164,7 +1164,7 @@ fn get_ua_stylesheets() -> Result<UserAgentStylesheets, &'static str> {
     for &(ref contents, ref url) in &opts::get().user_stylesheets {
         user_or_user_agent_stylesheets.push(DocumentStyleSheet(ServoArc::new(
             Stylesheet::from_bytes(
-                &contents,
+                contents,
                 UrlExtraData(url.get_arc()),
                 None,
                 None,
@@ -1179,7 +1179,7 @@ fn get_ua_stylesheets() -> Result<UserAgentStylesheets, &'static str> {
     }
 
     let quirks_mode_stylesheet = parse_ua_stylesheet(
-        &shared_lock,
+        shared_lock,
         "quirks-mode.css",
         &resources::read_bytes(Resource::QuirksModeCSS),
     )?;
@@ -1248,7 +1248,7 @@ struct RegisteredPaintersImpl(FnvHashMap<Atom, RegisteredPainterImpl>);
 impl RegisteredSpeculativePainters for RegisteredPaintersImpl {
     fn get(&self, name: &Atom) -> Option<&dyn RegisteredSpeculativePainter> {
         self.0
-            .get(&name)
+            .get(name)
             .map(|painter| painter as &dyn RegisteredSpeculativePainter)
     }
 }