clippy: Fix another set of clippy problems in components/script/dom (#31909)

* a reference to a reference

* length comparison to zero

* length comparison to zero

* length comparison to zero

components/script/dom/document.rs

@@ -933,7 +933,7 @@ impl Document {
     pub fn register_form_id_listener<T: ?Sized + FormControl>(&self, id: DOMString, listener: &T) {
         let mut map = self.form_id_listener_map.borrow_mut();
         let listener = listener.to_element();
-        let set = map.entry(Atom::from(id)).or_insert(HashSet::new());
+        let set = map.entry(Atom::from(id)).or_default();
         set.insert(Dom::from_ref(listener));
     }
 
@@ -1075,7 +1075,7 @@ impl Document {
 
     /// <https://html.spec.whatwg.org/multipage/#focus-fixup-rule>
     pub(crate) fn perform_focus_fixup_rule(&self, not_focusable: &Element) {
-        if Some(not_focusable) != self.focused.get().as_ref().map(|e| &**e) {
+        if Some(not_focusable) != self.focused.get().as_deref() {
             return;
         }
         self.request_focus(
@@ -1114,7 +1114,7 @@ impl Document {
             },
         };
         *self.focus_transaction.borrow_mut() = FocusTransaction::NotInTransaction;
-        if self.focused == possibly_focused.as_ref().map(|e| &**e) {
+        if self.focused == possibly_focused.as_deref() {
             return;
         }
         if let Some(ref elem) = self.focused.get() {
@@ -1129,7 +1129,7 @@ impl Document {
             }
         }
 
-        self.focused.set(possibly_focused.as_ref().map(|e| &**e));
+        self.focused.set(possibly_focused.as_deref());
 
         if let Some(ref elem) = self.focused.get() {
             elem.set_focus_state(true);
@@ -1152,7 +1152,7 @@ impl Document {
                 let (text, multiline) = if let Some(input) = elem.downcast::<HTMLInputElement>() {
                     (
                         Some((
-                            (&input.Value()).to_string(),
+                            input.Value().to_string(),
                             input.GetSelectionEnd().unwrap_or(0) as i32,
                         )),
                         false,
@@ -1160,7 +1160,7 @@ impl Document {
                 } else if let Some(textarea) = elem.downcast::<HTMLTextAreaElement>() {
                     (
                         Some((
-                            (&textarea.Value()).to_string(),
+                            textarea.Value().to_string(),
                             textarea.GetSelectionEnd().unwrap_or(0) as i32,
                         )),
                         true,
@@ -1188,7 +1188,7 @@ impl Document {
                 title.clone(),
             ));
             let global = self.window.upcast::<GlobalScope>();
-            if let Some(ref chan) = global.devtools_chan() {
+            if let Some(chan) = global.devtools_chan() {
                 let _ = chan.send(ScriptToDevtoolsControlMsg::TitleChanged(
                     global.pipeline_id(),
                     title,
@@ -3031,7 +3031,7 @@ fn get_registrable_domain_suffix_of_or_is_equal_to(
         let index = original_host.len().checked_sub(host.len())?;
         let (prefix, suffix) = original_host.split_at(index);
 
-        if !prefix.ends_with(".") {
+        if !prefix.ends_with('.') {
             return None;
         }
         if suffix != host {

components/script/dom/documentorshadowroot.rs

@@ -287,7 +287,7 @@ impl DocumentOrShadowRoot {
         assert!(element.upcast::<Node>().is_connected());
         assert!(!id.is_empty());
         let mut id_map = id_map.borrow_mut();
-        let elements = id_map.entry(id.clone()).or_insert(Vec::new());
+        let elements = id_map.entry(id.clone()).or_default();
         elements.insert_pre_order(element, &root);
     }
 }

components/script/dom/domtokenlist.rs

@@ -71,7 +71,7 @@ impl DOMTokenList {
     // https://dom.spec.whatwg.org/#concept-dtl-update
     fn perform_update_steps(&self, atoms: Vec<Atom>) {
         // Step 1
-        if !self.element.has_attribute(&self.local_name) && atoms.len() == 0 {
+        if !self.element.has_attribute(&self.local_name) && atoms.is_empty() {
             return;
         }
         // step 2

components/script/dom/element.rs

@@ -1217,7 +1217,7 @@ impl Element {
             // "3. If its namespace is non-null and its namespace prefix is prefix, then return
             // namespace."
             if element.namespace() != &ns!() &&
-                element.prefix().as_ref().map(|p| &**p) == prefix.as_ref().map(|p| &**p)
+                element.prefix().as_ref().map(|p| &**p) == prefix.as_deref()
             {
                 return element.namespace().clone();
             }
@@ -1548,7 +1548,7 @@ impl Element {
 
     pub fn set_attribute(&self, name: &LocalName, value: AttrValue) {
         assert!(name == &name.to_ascii_lowercase());
-        assert!(!name.contains(":"));
+        assert!(!name.contains(':'));
 
         self.set_first_matching_attribute(name.clone(), value, name.clone(), ns!(), None, |attr| {
             attr.local_name() == name
@@ -1725,7 +1725,7 @@ impl Element {
     pub fn get_tokenlist_attribute(&self, local_name: &LocalName) -> Vec<Atom> {
         self.get_attribute(&ns!(), local_name)
             .map(|attr| attr.value().as_tokens().to_vec())
-            .unwrap_or(vec![])
+            .unwrap_or_default()
     }
 
     pub fn set_tokenlist_attribute(&self, local_name: &LocalName, value: DOMString) {
@@ -3066,7 +3066,7 @@ impl VirtualMethods for Element {
     }
 
     fn bind_to_tree(&self, context: &BindContext) {
-        if let Some(ref s) = self.super_type() {
+        if let Some(s) = self.super_type() {
             s.bind_to_tree(context);
         }
 
@@ -3149,7 +3149,7 @@ impl VirtualMethods for Element {
     }
 
     fn children_changed(&self, mutation: &ChildrenMutation) {
-        if let Some(ref s) = self.super_type() {
+        if let Some(s) = self.super_type() {
             s.children_changed(mutation);
         }
 

components/script/dom/eventtarget.rs

@@ -204,7 +204,7 @@ impl CompiledEventListener {
                                 if let Ok(return_value) = return_value {
                                     rooted!(in(*cx) let return_value = return_value);
                                     if return_value.handle().is_boolean() &&
-                                        return_value.handle().to_boolean() == true
+                                        return_value.handle().to_boolean()
                                     {
                                         event.upcast::<Event>().PreventDefault();
                                     }
@@ -252,7 +252,7 @@ impl CompiledEventListener {
                             let value = value.handle();
 
                             //Step 5
-                            let should_cancel = value.is_boolean() && value.to_boolean() == false;
+                            let should_cancel = value.is_boolean() && !value.to_boolean();
 
                             if should_cancel {
                                 // FIXME: spec says to set the cancelled flag directly
@@ -342,7 +342,7 @@ impl EventListeners {
     fn has_listeners(&self) -> bool {
         // TODO: add, and take into account, a 'removed' field?
         // https://dom.spec.whatwg.org/#event-listener-removed
-        self.0.len() > 0
+        !self.0.is_empty()
     }
 }
 
@@ -417,7 +417,7 @@ impl EventTarget {
 
         let idx = entries
             .iter()
-            .position(|ref entry| matches!(entry.listener, EventListenerType::Inline(_)));
+            .position(|entry| matches!(entry.listener, EventListenerType::Inline(_)));
 
         match idx {
             Some(idx) => match listener {