style: Use style::One for Integer to avoid implementing Mul.

Differential Revision: https://phabricator.services.mozilla.com/D76207

components/style/values/generics/font.rs

@@ -5,9 +5,9 @@
 //! Generic types for font stuff.
 
 use crate::parser::{Parse, ParserContext};
+use crate::One;
 use byteorder::{BigEndian, ReadBytesExt};
 use cssparser::Parser;
-use num_traits::One;
 use std::fmt::{self, Write};
 use std::io::Cursor;
 use style_traits::{CssWriter, ParseError};
@@ -42,7 +42,7 @@ where
     {
         self.tag.to_css(dest)?;
         // Don't serialize the default value.
-        if self.value != Integer::one() {
+        if !self.value.is_one() {
             dest.write_char(' ')?;
             self.value.to_css(dest)?;
         }

components/style/values/specified/mod.rs

@@ -555,19 +555,15 @@ impl Zero for Integer {
     }
 }
 
-impl num_traits::One for Integer {
+impl One for Integer {
     #[inline]
     fn one() -> Self {
         Self::new(1)
     }
-}
 
-// This is not great, because it loses calc-ness, but it's necessary for One.
-impl ::std::ops::Mul<Integer> for Integer {
-    type Output = Self;
-
-    fn mul(self, other: Self) -> Self {
-        Self::new(self.value * other.value)
+    #[inline]
+    fn is_one(&self) -> bool {
+        self.value() == 1
     }
 }