Clippy: Fixed some clippy warnings (#31818)

* Fixed clippy warnings

* made changes for lowercase characters.

* changed is_lowercase() to is_ascii_lowercase()

* added std library function `is_ascii_uppercase()` and `is_ascii_lowercase()`

* made recommended changes

11 files changed, 57 insertions, 68 deletions

diff --git a/components/script/dom/headers.rs b/components/script/dom/headers.rs
index 3b966d1551b..8c8746ffbf2 100644
--- a/components/script/dom/headers.rs
+++ b/components/script/dom/headers.rs
@@ -567,5 +567,5 @@ pub fn extract_mime_type(headers: &HyperHeaders) -> Option<Vec<u8>> {
     }
 
     // Step 7, 8
-    return mime_type.map(|m| format!("{}", m).into_bytes());
+    mime_type.map(|m| format!("{}", m).into_bytes())
 }
diff --git a/components/script/dom/history.rs b/components/script/dom/history.rs
index c996cf87ccd..465d4153c3c 100644
--- a/components/script/dom/history.rs
+++ b/components/script/dom/history.rs
@@ -121,7 +121,7 @@ impl History {
                 };
                 let global_scope = self.window.upcast::<GlobalScope>();
                 rooted!(in(*GlobalScope::get_cx()) let mut state = UndefinedValue());
-                if let Err(_) = structuredclone::read(global_scope, data, state.handle_mut()) {
+                if structuredclone::read(global_scope, data, state.handle_mut()).is_err() {
                     warn!("Error reading structuredclone data");
                 }
                 self.state.set(state.get());
@@ -270,7 +270,7 @@ impl History {
         // Step 11
         let global_scope = self.window.upcast::<GlobalScope>();
         rooted!(in(*cx) let mut state = UndefinedValue());
-        if let Err(_) = structuredclone::read(global_scope, serialized_data, state.handle_mut()) {
+        if structuredclone::read(global_scope, serialized_data, state.handle_mut()).is_err() {
             warn!("Error reading structuredclone data");
         }
 
diff --git a/components/script/dom/htmlanchorelement.rs b/components/script/dom/htmlanchorelement.rs
index 1d720e7b955..e1aad200e55 100644
--- a/components/script/dom/htmlanchorelement.rs
+++ b/components/script/dom/htmlanchorelement.rs
@@ -601,13 +601,13 @@ pub fn get_element_target(subject: &Element) -> Option<DOMString> {
         Some(doc) => {
             let element = doc.upcast::<Element>();
             if element.has_attribute(&local_name!("target")) {
-                return Some(element.get_string_attribute(&local_name!("target")));
+                Some(element.get_string_attribute(&local_name!("target")))
             } else {
-                return None;
+                None
             }
         },
-        None => return None,
-    };
+        None => None,
+    }
 }
 
 /// <https://html.spec.whatwg.org/multipage/#get-an-element's-noopener>
@@ -625,9 +625,9 @@ pub fn get_element_noopener(subject: &Element, target_attribute_value: Option<DO
         Some(rel) => rel.Value(),
         None => return target_is_blank,
     };
-    return link_types.contains("noreferrer") ||
+    link_types.contains("noreferrer") ||
         link_types.contains("noopener") ||
-        (!link_types.contains("opener") && target_is_blank);
+        (!link_types.contains("opener") && target_is_blank)
 }
 
 /// <https://html.spec.whatwg.org/multipage/#following-hyperlinks-2>
diff --git a/components/script/dom/htmlbodyelement.rs b/components/script/dom/htmlbodyelement.rs
index 64f482f054c..4dcbfe0b80f 100644
--- a/components/script/dom/htmlbodyelement.rs
+++ b/components/script/dom/htmlbodyelement.rs
@@ -145,7 +145,7 @@ impl VirtualMethods for HTMLBodyElement {
     }
 
     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);
         }
 
diff --git a/components/script/dom/htmlbuttonelement.rs b/components/script/dom/htmlbuttonelement.rs
index dc6c799005f..a851b1ecc3c 100755
--- a/components/script/dom/htmlbuttonelement.rs
+++ b/components/script/dom/htmlbuttonelement.rs
@@ -229,8 +229,8 @@ impl VirtualMethods for HTMLButtonElement {
 
     fn attribute_mutated(&self, attr: &Attr, mutation: AttributeMutation) {
         self.super_type().unwrap().attribute_mutated(attr, mutation);
-        match attr.local_name() {
-            &local_name!("disabled") => {
+        match *attr.local_name() {
+            local_name!("disabled") => {
                 let el = self.upcast::<Element>();
                 match mutation {
                     AttributeMutation::Set(Some(_)) => {},
@@ -248,7 +248,7 @@ impl VirtualMethods for HTMLButtonElement {
                 self.validity_state()
                     .perform_validation_and_update(ValidationFlags::all());
             },
-            &local_name!("type") => match mutation {
+            local_name!("type") => match mutation {
                 AttributeMutation::Set(_) => {
                     let value = match &**attr.value() {
                         "reset" => ButtonType::Reset,
@@ -263,7 +263,7 @@ impl VirtualMethods for HTMLButtonElement {
                     self.button_type.set(ButtonType::Submit);
                 },
             },
-            &local_name!("form") => {
+            local_name!("form") => {
                 self.form_attribute_mutated(mutation);
                 self.validity_state()
                     .perform_validation_and_update(ValidationFlags::empty());
@@ -273,7 +273,7 @@ impl VirtualMethods for HTMLButtonElement {
     }
 
     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);
         }
 
@@ -306,7 +306,7 @@ impl FormControl for HTMLButtonElement {
         self.form_owner.set(form);
     }
 
-    fn to_element<'a>(&'a self) -> &'a Element {
+    fn to_element(&self) -> &Element {
         self.upcast::<Element>()
     }
 }
diff --git a/components/script/dom/htmlcanvaselement.rs b/components/script/dom/htmlcanvaselement.rs
index dce5fd0ea5e..a2b6aa6a2a8 100644
--- a/components/script/dom/htmlcanvaselement.rs
+++ b/components/script/dom/htmlcanvaselement.rs
@@ -179,7 +179,7 @@ impl LayoutHTMLCanvasElementHelpers for LayoutDom<'_, HTMLCanvasElement> {
     #[allow(unsafe_code)]
     fn get_canvas_id_for_layout(self) -> CanvasId {
         unsafe {
-            let canvas = &*self.unsafe_get();
+            let canvas = self.unsafe_get();
             if let &Some(CanvasContext::Context2d(ref context)) = canvas.context.borrow_for_layout()
             {
                 context.to_layout().get_canvas_id()
@@ -277,7 +277,7 @@ impl HTMLCanvasElement {
     /// Gets the base WebGLRenderingContext for WebGL or WebGL 2, if exists.
     pub fn get_base_webgl_context(&self) -> Option<DomRoot<WebGLRenderingContext>> {
         match *self.context.borrow() {
-            Some(CanvasContext::WebGL(ref context)) => Some(DomRoot::from_ref(&*context)),
+            Some(CanvasContext::WebGL(ref context)) => Some(DomRoot::from_ref(context)),
             Some(CanvasContext::WebGL2(ref context)) => Some(context.base_context()),
             _ => None,
         }
@@ -460,9 +460,9 @@ impl VirtualMethods for HTMLCanvasElement {
     }
 
     fn parse_plain_attribute(&self, name: &LocalName, value: DOMString) -> AttrValue {
-        match name {
-            &local_name!("width") => AttrValue::from_u32(value.into(), DEFAULT_WIDTH),
-            &local_name!("height") => AttrValue::from_u32(value.into(), DEFAULT_HEIGHT),
+        match *name {
+            local_name!("width") => AttrValue::from_u32(value.into(), DEFAULT_WIDTH),
+            local_name!("height") => AttrValue::from_u32(value.into(), DEFAULT_HEIGHT),
             _ => self
                 .super_type()
                 .unwrap()
diff --git a/components/script/dom/htmlcollection.rs b/components/script/dom/htmlcollection.rs
index 5a01e5be773..cfcc8b5f2ef 100644
--- a/components/script/dom/htmlcollection.rs
+++ b/components/script/dom/htmlcollection.rs
@@ -195,7 +195,7 @@ impl HTMLCollection {
             None => elem.local_name() == qualified_name,
             Some(prefix) => {
                 qualified_name.starts_with(&**prefix) &&
-                    qualified_name.find(":") == Some(prefix.len()) &&
+                    qualified_name.find(':') == Some(prefix.len()) &&
                     qualified_name.ends_with(&**elem.local_name())
             },
         }
@@ -295,7 +295,7 @@ impl HTMLCollection {
             .filter(move |element| self.filter.filter(element, &self.root))
     }
 
-    pub fn elements_iter<'a>(&'a self) -> impl Iterator<Item = DomRoot<Element>> + 'a {
+    pub fn elements_iter(&self) -> impl Iterator<Item = DomRoot<Element>> + '_ {
         // Iterate forwards from the root.
         self.elements_iter_after(&self.root)
     }
diff --git a/components/script/dom/htmlelement.rs b/components/script/dom/htmlelement.rs
index 8a199ec9b4d..f40c5439de7 100644
--- a/components/script/dom/htmlelement.rs
+++ b/components/script/dom/htmlelement.rs
@@ -559,19 +559,11 @@ fn append_text_node_to_fragment(document: &Document, fragment: &DocumentFragment
 static DATA_PREFIX: &str = "data-";
 static DATA_HYPHEN_SEPARATOR: char = '\x2d';
 
-fn is_ascii_uppercase(c: char) -> bool {
-    'A' <= c && c <= 'Z'
-}
-
-fn is_ascii_lowercase(c: char) -> bool {
-    'a' <= c && c <= 'w'
-}
-
 fn to_snake_case(name: DOMString) -> DOMString {
     let mut attr_name = String::with_capacity(name.len() + DATA_PREFIX.len());
     attr_name.push_str(DATA_PREFIX);
     for ch in name.chars() {
-        if is_ascii_uppercase(ch) {
+        if ch.is_ascii_uppercase() {
             attr_name.push(DATA_HYPHEN_SEPARATOR);
             attr_name.push(ch.to_ascii_lowercase());
         } else {
@@ -591,7 +583,7 @@ fn to_camel_case(name: &str) -> Option<DOMString> {
         return None;
     }
     let name = &name[5..];
-    let has_uppercase = name.chars().any(|curr_char| is_ascii_uppercase(curr_char));
+    let has_uppercase = name.chars().any(|curr_char| curr_char.is_ascii_uppercase());
     if has_uppercase {
         return None;
     }
@@ -601,7 +593,7 @@ fn to_camel_case(name: &str) -> Option<DOMString> {
         //check for hyphen followed by character
         if curr_char == DATA_HYPHEN_SEPARATOR {
             if let Some(next_char) = name_chars.next() {
-                if is_ascii_lowercase(next_char) {
+                if next_char.is_ascii_lowercase() {
                     result.push(next_char.to_ascii_uppercase());
                 } else {
                     result.push(curr_char);
@@ -623,7 +615,7 @@ impl HTMLElement {
             .chars()
             .skip_while(|&ch| ch != '\u{2d}')
             .nth(1)
-            .map_or(false, |ch| ch >= 'a' && ch <= 'z')
+            .map_or(false, |ch| ch.is_ascii_lowercase())
         {
             return Err(Error::Syntax);
         }
@@ -670,16 +662,16 @@ impl HTMLElement {
     // https://html.spec.whatwg.org/multipage/#category-listed
     pub fn is_listed_element(&self) -> bool {
         match self.upcast::<Node>().type_id() {
-            NodeTypeId::Element(ElementTypeId::HTMLElement(type_id)) => match type_id {
+            NodeTypeId::Element(ElementTypeId::HTMLElement(type_id)) => matches!(
+                type_id,
                 HTMLElementTypeId::HTMLButtonElement |
-                HTMLElementTypeId::HTMLFieldSetElement |
-                HTMLElementTypeId::HTMLInputElement |
-                HTMLElementTypeId::HTMLObjectElement |
-                HTMLElementTypeId::HTMLOutputElement |
-                HTMLElementTypeId::HTMLSelectElement |
-                HTMLElementTypeId::HTMLTextAreaElement => true,
-                _ => false,
-            },
+                    HTMLElementTypeId::HTMLFieldSetElement |
+                    HTMLElementTypeId::HTMLInputElement |
+                    HTMLElementTypeId::HTMLObjectElement |
+                    HTMLElementTypeId::HTMLOutputElement |
+                    HTMLElementTypeId::HTMLSelectElement |
+                    HTMLElementTypeId::HTMLTextAreaElement
+            ),
             _ => false,
         }
     }
@@ -851,9 +843,9 @@ impl VirtualMethods for HTMLElement {
     }
 
     fn parse_plain_attribute(&self, name: &LocalName, value: DOMString) -> AttrValue {
-        match name {
-            &local_name!("itemprop") => AttrValue::from_serialized_tokenlist(value.into()),
-            &local_name!("itemtype") => AttrValue::from_serialized_tokenlist(value.into()),
+        match *name {
+            local_name!("itemprop") => AttrValue::from_serialized_tokenlist(value.into()),
+            local_name!("itemtype") => AttrValue::from_serialized_tokenlist(value.into()),
             _ => self
                 .super_type()
                 .unwrap()
diff --git a/components/script/dom/htmlfieldsetelement.rs b/components/script/dom/htmlfieldsetelement.rs
index b29f4b471b0..f944ccddc92 100644
--- a/components/script/dom/htmlfieldsetelement.rs
+++ b/components/script/dom/htmlfieldsetelement.rs
@@ -158,8 +158,8 @@ impl VirtualMethods for HTMLFieldSetElement {
 
     fn attribute_mutated(&self, attr: &Attr, mutation: AttributeMutation) {
         self.super_type().unwrap().attribute_mutated(attr, mutation);
-        match attr.local_name() {
-            &local_name!("disabled") => {
+        match *attr.local_name() {
+            local_name!("disabled") => {
                 let disabled_state = match mutation {
                     AttributeMutation::Set(None) => true,
                     AttributeMutation::Set(Some(_)) => {
@@ -219,7 +219,7 @@ impl VirtualMethods for HTMLFieldSetElement {
                 }
                 el.update_sequentially_focusable_status();
             },
-            &local_name!("form") => {
+            local_name!("form") => {
                 self.form_attribute_mutated(mutation);
             },
             _ => {},
@@ -236,7 +236,7 @@ impl FormControl for HTMLFieldSetElement {
         self.form_owner.set(form);
     }
 
-    fn to_element<'a>(&'a self) -> &'a Element {
+    fn to_element(&self) -> &Element {
         self.upcast::<Element>()
     }
 }
diff --git a/components/script/dom/htmlfontelement.rs b/components/script/dom/htmlfontelement.rs
index 9bdd32bb5c4..641dd8a92f3 100644
--- a/components/script/dom/htmlfontelement.rs
+++ b/components/script/dom/htmlfontelement.rs
@@ -92,10 +92,10 @@ impl VirtualMethods for HTMLFontElement {
     }
 
     fn parse_plain_attribute(&self, name: &LocalName, value: DOMString) -> AttrValue {
-        match name {
-            &local_name!("face") => AttrValue::from_atomic(value.into()),
-            &local_name!("color") => AttrValue::from_legacy_color(value.into()),
-            &local_name!("size") => parse_size(&value),
+        match *name {
+            local_name!("face") => AttrValue::from_atomic(value.into()),
+            local_name!("color") => AttrValue::from_legacy_color(value.into()),
+            local_name!("size") => parse_size(&value),
             _ => self
                 .super_type()
                 .unwrap()
@@ -174,7 +174,7 @@ fn parse_size(mut input: &str) -> AttrValue {
 
     // Step 9
     match parse_mode {
-        ParseMode::RelativePlus => value = 3 + value,
+        ParseMode::RelativePlus => value += 3,
         ParseMode::RelativeMinus => value = 3 - value,
         ParseMode::Absolute => (),
     }
diff --git a/components/script/dom/htmlformelement.rs b/components/script/dom/htmlformelement.rs
index a9c5c910ad6..cd7c4411892 100644
--- a/components/script/dom/htmlformelement.rs
+++ b/components/script/dom/htmlformelement.rs
@@ -180,7 +180,7 @@ impl HTMLFormElement {
             .iter()
             .filter(|n| HTMLFormElement::filter_for_radio_list(mode, n, name))
             .nth(index as usize)
-            .and_then(|n| Some(DomRoot::from_ref(n.upcast::<Node>())))
+            .map(|n| DomRoot::from_ref(n.upcast::<Node>()))
     }
 
     pub fn count_for_radio_list(&self, mode: RadioListMode, name: &Atom) -> u32 {
@@ -441,14 +441,14 @@ impl HTMLFormElementMethods for HTMLFormElement {
         past_names_map.insert(
             name,
             (
-                Dom::from_ref(&*element_node.downcast::<Element>().unwrap()),
+                Dom::from_ref(element_node.downcast::<Element>().unwrap()),
                 NoTrace(Instant::now()),
             ),
         );
 
         // Step 6
         return Some(RadioNodeListOrElement::Element(DomRoot::from_ref(
-            &*element_node.downcast::<Element>().unwrap(),
+            element_node.downcast::<Element>().unwrap(),
         )));
     }
 
@@ -486,10 +486,7 @@ impl HTMLFormElementMethods for HTMLFormElement {
 
         impl SourcedNameSource {
             fn is_past(&self) -> bool {
-                match self {
-                    SourcedNameSource::Past(..) => true,
-                    _ => false,
-                }
+                matches!(self, SourcedNameSource::Past(..))
             }
         }
 
@@ -512,7 +509,7 @@ impl HTMLFormElementMethods for HTMLFormElement {
                 if let Some(id_atom) = child.get_id() {
                     let entry = SourcedName {
                         name: id_atom,
-                        element: DomRoot::from_ref(&*child),
+                        element: DomRoot::from_ref(child),
                         source: SourcedNameSource::Id,
                     };
                     sourced_names_vec.push(entry);
@@ -520,7 +517,7 @@ impl HTMLFormElementMethods for HTMLFormElement {
                 if let Some(name_atom) = child.get_name() {
                     let entry = SourcedName {
                         name: name_atom,
-                        element: DomRoot::from_ref(&*child),
+                        element: DomRoot::from_ref(child),
                         source: SourcedNameSource::Name,
                     };
                     sourced_names_vec.push(entry);
@@ -534,7 +531,7 @@ impl HTMLFormElementMethods for HTMLFormElement {
                 if let Some(id_atom) = child.get_id() {
                     let entry = SourcedName {
                         name: id_atom,
-                        element: DomRoot::from_ref(&*child),
+                        element: DomRoot::from_ref(child),
                         source: SourcedNameSource::Id,
                     };
                     sourced_names_vec.push(entry);
@@ -542,7 +539,7 @@ impl HTMLFormElementMethods for HTMLFormElement {
                 if let Some(name_atom) = child.get_name() {
                     let entry = SourcedName {
                         name: name_atom,
-                        element: DomRoot::from_ref(&*child),
+                        element: DomRoot::from_ref(child),
                         source: SourcedNameSource::Name,
                     };
                     sourced_names_vec.push(entry);
@@ -612,7 +609,7 @@ impl HTMLFormElementMethods for HTMLFormElement {
             }
         }
 
-        return names_vec;
+        names_vec
     }
 
     /// <https://html.spec.whatwg.org/multipage/#dom-form-checkvalidity>