style: Make CalcNode the specified representation of <length> and <length-percentage> values.

This is the meat of the patch. There are a couple improvements done in a couple
later patches which should hopefully be straight-forward.

Differential Revision: https://phabricator.services.mozilla.com/D63397

components/style/values/animated/length.rs

@@ -1,39 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-//! Animation implementation for various length-related types.
-
-use super::{Animate, Procedure};
-use crate::values::computed::length::LengthPercentage;
-use crate::values::computed::Percentage;
-use style_traits::values::specified::AllowedNumericType;
-
-/// <https://drafts.csswg.org/css-transitions/#animtype-lpcalc>
-impl Animate for LengthPercentage {
-    #[inline]
-    fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
-        let animate_percentage_half = |this: Option<Percentage>, other: Option<Percentage>| {
-            if this.is_none() && other.is_none() {
-                return Ok(None);
-            }
-            let this = this.unwrap_or_default();
-            let other = other.unwrap_or_default();
-            Ok(Some(this.animate(&other, procedure)?))
-        };
-
-        let length = self
-            .unclamped_length()
-            .animate(&other.unclamped_length(), procedure)?;
-        let percentage =
-            animate_percentage_half(self.specified_percentage(), other.specified_percentage())?;
-
-        // Gets clamped as needed after the animation if needed, so no need to
-        // specify any particular AllowedNumericType.
-        Ok(LengthPercentage::new_calc(
-            length,
-            percentage,
-            AllowedNumericType::All,
-        ))
-    }
-}

components/style/values/animated/mod.rs

@@ -23,7 +23,6 @@ pub mod color;
 pub mod effects;
 mod font;
 mod grid;
-mod length;
 mod svg;
 pub mod transform;
 
@@ -454,6 +453,16 @@ where
     }
 }
 
+impl<T> ToAnimatedZero for Box<[T]>
+where
+    T: ToAnimatedZero,
+{
+    #[inline]
+    fn to_animated_zero(&self) -> Result<Self, ()> {
+        self.iter().map(|v| v.to_animated_zero()).collect()
+    }
+}
+
 impl<T> ToAnimatedZero for crate::OwnedSlice<T>
 where
     T: ToAnimatedZero,