Auto merge of #25818 - mrobinson:transforms, r=SimonSapin

Add initial support for transforms to layout_2020

---
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- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #___ (GitHub issue number if applicable)

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- [x] There are tests for these changes OR
- [ ] These changes do not require tests because ___

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components/style/properties/longhands/box.mako.rs

@@ -345,7 +345,6 @@ ${helpers.predefined_type(
     "Transform",
     "generics::transform::Transform::none()",
     engines="gecko servo-2013 servo-2020",
-    servo_2020_pref="layout.2020.unimplemented",
     extra_prefixes=transform_extra_prefixes,
     animation_value_type="ComputedValue",
     flags="CREATES_STACKING_CONTEXT FIXPOS_CB CAN_ANIMATE_ON_COMPOSITOR",
@@ -549,7 +548,7 @@ ${helpers.predefined_type(
     "perspective",
     "Perspective",
     "computed::Perspective::none()",
-    engines="gecko servo-2013",
+    engines="gecko servo-2013 servo-2020",
     gecko_ffi_name="mChildPerspective",
     spec="https://drafts.csswg.org/css-transforms/#perspective",
     extra_prefixes=transform_extra_prefixes,
@@ -562,7 +561,7 @@ ${helpers.predefined_type(
     "perspective-origin",
     "Position",
     "computed::position::Position::center()",
-    engines="gecko servo-2013",
+    engines="gecko servo-2013 servo-2020",
     boxed=True,
     extra_prefixes=transform_extra_prefixes,
     spec="https://drafts.csswg.org/css-transforms-2/#perspective-origin-property",
@@ -573,7 +572,7 @@ ${helpers.predefined_type(
 ${helpers.single_keyword(
     "backface-visibility",
     "visible hidden",
-    engines="gecko servo-2013",
+    engines="gecko servo-2013 servo-2020",
     spec="https://drafts.csswg.org/css-transforms/#backface-visibility-property",
     extra_prefixes=transform_extra_prefixes,
     animation_value_type="discrete",
@@ -595,7 +594,6 @@ ${helpers.predefined_type(
     "TransformStyle",
     "computed::TransformStyle::Flat",
     engines="gecko servo-2013 servo-2020",
-    servo_2020_pref="layout.2020.unimplemented",
     spec="https://drafts.csswg.org/css-transforms-2/#transform-style-property",
     needs_context=False,
     extra_prefixes=transform_extra_prefixes,
@@ -608,7 +606,7 @@ ${helpers.predefined_type(
     "transform-origin",
     "TransformOrigin",
     "computed::TransformOrigin::initial_value()",
-    engines="gecko servo-2013",
+    engines="gecko servo-2013 servo-2020",
     animation_value_type="ComputedValue",
     extra_prefixes=transform_extra_prefixes,
     gecko_ffi_name="mTransformOrigin",

components/style/values/generics/transform.rs

@@ -11,7 +11,6 @@ use crate::values::specified::length::Length as SpecifiedLength;
 use crate::values::specified::length::LengthPercentage as SpecifiedLengthPercentage;
 use crate::values::{computed, CSSFloat};
 use crate::Zero;
-use app_units::Au;
 use euclid;
 use euclid::default::{Rect, Transform3D};
 use std::fmt::{self, Write};
@@ -329,7 +328,7 @@ where
 /// Convert a length type into the absolute lengths.
 pub trait ToAbsoluteLength {
     /// Returns the absolute length as pixel value.
-    fn to_pixel_length(&self, containing_len: Option<Au>) -> Result<CSSFloat, ()>;
+    fn to_pixel_length(&self, containing_len: Option<ComputedLength>) -> Result<CSSFloat, ()>;
 }
 
 impl ToAbsoluteLength for SpecifiedLength {
@@ -337,7 +336,7 @@ impl ToAbsoluteLength for SpecifiedLength {
     // parsing a transform list of DOMMatrix because we want to return a DOM Exception
     // if there is relative length.
     #[inline]
-    fn to_pixel_length(&self, _containing_len: Option<Au>) -> Result<CSSFloat, ()> {
+    fn to_pixel_length(&self, _containing_len: Option<ComputedLength>) -> Result<CSSFloat, ()> {
         match *self {
             SpecifiedLength::NoCalc(len) => len.to_computed_pixel_length_without_context(),
             SpecifiedLength::Calc(ref calc) => calc.to_computed_pixel_length_without_context(),
@@ -350,7 +349,7 @@ impl ToAbsoluteLength for SpecifiedLengthPercentage {
     // parsing a transform list of DOMMatrix because we want to return a DOM Exception
     // if there is relative length.
     #[inline]
-    fn to_pixel_length(&self, _containing_len: Option<Au>) -> Result<CSSFloat, ()> {
+    fn to_pixel_length(&self, _containing_len: Option<ComputedLength>) -> Result<CSSFloat, ()> {
         use self::SpecifiedLengthPercentage::*;
         match *self {
             Length(len) => len.to_computed_pixel_length_without_context(),
@@ -362,16 +361,16 @@ impl ToAbsoluteLength for SpecifiedLengthPercentage {
 
 impl ToAbsoluteLength for ComputedLength {
     #[inline]
-    fn to_pixel_length(&self, _containing_len: Option<Au>) -> Result<CSSFloat, ()> {
+    fn to_pixel_length(&self, _containing_len: Option<ComputedLength>) -> Result<CSSFloat, ()> {
         Ok(self.px())
     }
 }
 
 impl ToAbsoluteLength for ComputedLengthPercentage {
     #[inline]
-    fn to_pixel_length(&self, containing_len: Option<Au>) -> Result<CSSFloat, ()> {
+    fn to_pixel_length(&self, containing_len: Option<ComputedLength>) -> Result<CSSFloat, ()> {
         match containing_len {
-            Some(relative_len) => Ok(self.to_pixel_length(relative_len).px()),
+            Some(relative_len) => Ok(self.resolve(relative_len).px()),
             // If we don't have reference box, we cannot resolve the used value,
             // so only retrieve the length part. This will be used for computing
             // distance without any layout info.
@@ -388,7 +387,10 @@ pub trait ToMatrix {
     fn is_3d(&self) -> bool;
 
     /// Return the equivalent 3d matrix.
-    fn to_3d_matrix(&self, reference_box: Option<&Rect<Au>>) -> Result<Transform3D<f64>, ()>;
+    fn to_3d_matrix(
+        &self,
+        reference_box: Option<&Rect<ComputedLength>>,
+    ) -> Result<Transform3D<f64>, ()>;
 }
 
 /// A little helper to deal with both specified and computed angles.
@@ -434,7 +436,10 @@ where
     /// However, for specified TransformOperation, we will return Err(()) if there is any relative
     /// lengths because the only caller, DOMMatrix, doesn't accept relative lengths.
     #[inline]
-    fn to_3d_matrix(&self, reference_box: Option<&Rect<Au>>) -> Result<Transform3D<f64>, ()> {
+    fn to_3d_matrix(
+        &self,
+        reference_box: Option<&Rect<ComputedLength>>,
+    ) -> Result<Transform3D<f64>, ()> {
         use self::TransformOperation::*;
         use std::f64;
 
@@ -537,7 +542,7 @@ impl<T: ToMatrix> Transform<T> {
     #[cfg_attr(rustfmt, rustfmt_skip)]
     pub fn to_transform_3d_matrix(
         &self,
-        reference_box: Option<&Rect<Au>>
+        reference_box: Option<&Rect<ComputedLength>>
     ) -> Result<(Transform3D<CSSFloat>, bool), ()> {
         let cast_3d_transform = |m: Transform3D<f64>| -> Transform3D<CSSFloat> {
             use std::{f32, f64};
@@ -557,7 +562,7 @@ impl<T: ToMatrix> Transform<T> {
     /// Same as Transform::to_transform_3d_matrix but a f64 version.
     pub fn to_transform_3d_matrix_f64(
         &self,
-        reference_box: Option<&Rect<Au>>,
+        reference_box: Option<&Rect<ComputedLength>>,
     ) -> Result<(Transform3D<f64>, bool), ()> {
         // We intentionally use Transform3D<f64> during computation to avoid error propagation
         // because using f32 to compute triangle functions (e.g. in create_rotation()) is not