clippy: Fix various clippy warnings in `components/scripts/dom/bindin…

…gs` (#31901)

* single-character string constant used as pattern

* singuse of  with literal radix of 16

components/script/dom/bindings/root.rs

@@ -237,7 +237,7 @@ pub struct ThreadLocalStackRoots<'a>(PhantomData<&'a u32>);
 
 impl<'a> ThreadLocalStackRoots<'a> {
  pub fn new(roots: &'a RootCollection) -> Self {
- STACK_ROOTS.with(|ref r| r.set(Some(roots)));
+ STACK_ROOTS.with(|r| r.set(Some(roots)));
  ThreadLocalStackRoots(PhantomData)
  }
 }

components/script/dom/bindings/str.rs

@@ -443,7 +443,7 @@ impl DOMString {
  if !(
  // A valid number is the same as what rust considers to be valid,
  // except for +1., NaN, and Infinity.
- val.is_infinite() || val.is_nan() || input.ends_with(".") || input.starts_with("+")
+ val.is_infinite() || val.is_nan() || input.ends_with(".") || input.starts_with('+')
  ) {
  return Some(val);
  }
@@ -529,7 +529,7 @@ impl DOMString {
  pub fn is_valid_simple_color_string(&self) -> bool {
  let mut chars = self.0.chars();
  if self.0.len() == 7 && chars.next() == Some('#') {
- chars.all(|c| c.is_digit(16))
+ chars.all(|c| c.is_ascii_hexdigit())
  } else {
  false
  }