style: Use the standalone struct and enum for the flags in SVG path.

We define the standalone types for using derive macro easily and overriding
the behaviors of this traits. This could avoid defining the general
behavior of booleans.

Depends on D4788

Differential Revision: https://phabricator.services.mozilla.com/D4813

components/style/values/animated/mod.rs

@@ -141,20 +141,6 @@ impl Animate for f64 {
     }
 }
 
-/// This is only used in SVG PATH. We return Err(()) if the flags are mismatched.
-// FIXME: Bug 653928: If we want to do interpolation on the flags in Arc, we have to update this
-// because `absolute`, `large_arc_flag`, and `sweep_flag` are using this implementation for now.
-impl Animate for bool {
-    #[inline]
-    fn animate(&self, other: &Self, _procedure: Procedure) -> Result<Self, ()> {
-        if *self == *other {
-            Ok(*other)
-        } else {
-            Err(())
-        }
-    }
-}
-
 impl<T> Animate for Option<T>
 where
     T: Animate,