selectors: Fix some unused mut warnings.

components/selectors/matching.rs

@@ -456,11 +456,12 @@ where
 }
 
 /// Matches a complex selector.
-pub fn matches_complex_selector<E, F>(mut iter: SelectorIter<E::Impl>,
-                                      element: &E,
-                                      mut context: &mut LocalMatchingContext<E::Impl>,
-                                      flags_setter: &mut F)
-                                      -> bool
+pub fn matches_complex_selector<E, F>(
+    mut iter: SelectorIter<E::Impl>,
+    element: &E,
+    context: &mut LocalMatchingContext<E::Impl>,
+    flags_setter: &mut F,
+) -> bool
     where E: Element,
           F: FnMut(&E, ElementSelectorFlags),
 {

components/selectors/parser.rs

@@ -1464,9 +1464,11 @@ fn parse_negation<'i, 't, P, E, Impl>(parser: &P,
 fn parse_compound_selector<'i, 't, P, E, Impl>(
     parser: &P,
     input: &mut CssParser<'i, 't>,
-    mut builder: &mut SelectorBuilder<Impl>)
-    -> Result<bool, ParseError<'i, SelectorParseError<'i, E>>>
-    where P: Parser<'i, Impl=Impl, Error=E>, Impl: SelectorImpl
+    builder: &mut SelectorBuilder<Impl>,
+) -> Result<bool, ParseError<'i, SelectorParseError<'i, E>>>
+where
+    P: Parser<'i, Impl=Impl, Error=E>,
+    Impl: SelectorImpl,
 {
     // Consume any leading whitespace.
     loop {