style: Move the animation code of transform into a different file.

Basically, most of the animation code of transform don't need mako, so
we could move them into values/animated/transform.rs.

However, we still use mako to generate some code to make the methods of
Matrix3D simpler, so I still leave them in animated_properties.mako.rs.

Differential Revision: https://phabricator.services.mozilla.com/D11934

components/style/values/animated/mod.rs

@@ -14,12 +14,14 @@ use crate::values::computed::length::CalcLengthOrPercentage;
 use crate::values::computed::url::ComputedUrl;
 use crate::values::computed::Angle as ComputedAngle;
 use crate::values::computed::BorderCornerRadius as ComputedBorderCornerRadius;
+use crate::values::CSSFloat;
 use euclid::{Point2D, Size2D};
 use smallvec::SmallVec;
 use std::cmp;
 
 pub mod color;
 pub mod effects;
+pub mod transform;
 mod font;
 mod length;
 mod svg;
@@ -86,6 +88,15 @@ pub fn compare_property_priority(a: &PropertyId, b: &PropertyId) -> cmp::Orderin
         .then_with(|| a.idl_name_sort_order().cmp(&b.idl_name_sort_order()))
 }
 
+/// A helper function to animate two multiplicative factor.
+pub fn animate_multiplicative_factor(
+    this: CSSFloat,
+    other: CSSFloat,
+    procedure: Procedure,
+) -> Result<CSSFloat, ()> {
+    Ok((this - 1.).animate(&(other - 1.), procedure)? + 1.)
+}
+
 /// Animate from one value to another.
 ///
 /// This trait is derivable with `#[derive(Animate)]`. The derived