style: Use ? in Option more often.

components/style/properties/declaration_block.rs

@@ -140,15 +140,10 @@ impl<'a> Iterator for NormalDeclarationIterator<'a> {
 
     fn next(&mut self) -> Option<Self::Item> {
         loop {
-            let next = self.0.iter.next();
+            let (decl, importance) = self.0.iter.next()?;
-            match next {
-                Some((decl, importance)) => {
             if !importance {
                 return Some(decl);
             }
-                },
-                None => return None,
-            }
         }
     }
 
@@ -187,11 +182,7 @@ impl<'a, 'cx, 'cx_a:'cx> Iterator for AnimationValueIterator<'a, 'cx, 'cx_a> {
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
         loop {
-            let next = self.iter.next();
+            let decl = self.iter.next()?;
-            let decl = match next {
-                Some(decl) => decl,
-                None => return None,
-            };
 
             let animation = AnimationValue::from_declaration(
                 decl,

components/style/properties/properties.mako.rs

@@ -850,10 +850,12 @@ impl ShorthandId {
     /// Finds and returns an appendable value for the given declarations.
     ///
     /// Returns the optional appendable value.
-    pub fn get_shorthand_appendable_value<'a, I>(self,
+    pub fn get_shorthand_appendable_value<'a, I>(
-                                                 declarations: I)
+        self,
-                                                 -> Option<AppendableValue<'a, I::IntoIter>>
+        declarations: I,
-        where I: IntoIterator<Item=&'a PropertyDeclaration>,
+    ) -> Option<AppendableValue<'a, I::IntoIter>>
+    where
+        I: IntoIterator<Item=&'a PropertyDeclaration>,
         I::IntoIter: Clone,
     {
         let declarations = declarations.into_iter();
@@ -862,10 +864,7 @@ impl ShorthandId {
         let mut declarations2 = declarations.clone();
         let mut declarations3 = declarations.clone();
 
-        let first_declaration = match declarations2.next() {
+        let first_declaration = declarations2.next()?;
-            Some(declaration) => declaration,
-            None => return None
-        };
 
         // https://drafts.csswg.org/css-variables/#variables-in-shorthands
         if let Some(css) = first_declaration.with_variables_from_shorthand(self) {