style: Replace transform style defines to an enum class.

Differential Revision: https://phabricator.services.mozilla.com/D61388

components/style/properties/gecko.mako.rs

@@ -53,7 +53,6 @@ use crate::values::computed::BorderStyle;
 use crate::values::computed::font::FontSize;
 use crate::values::generics::column::ColumnCount;
 use crate::values::generics::image::ImageLayer;
-use crate::values::generics::transform::TransformStyle;
 use crate::values::generics::url::UrlOrNone;
 
 
@@ -1473,7 +1472,7 @@ fn static_assert() {
                           animation-iteration-count animation-timing-function
                           clear transition-duration transition-delay
                           transition-timing-function transition-property
-                          transform-style shape-outside -webkit-line-clamp""" %>
+                          shape-outside -webkit-line-clamp""" %>
 <%self:impl_trait style_struct_name="Box" skip_longhands="${skip_box_longhands}">
     #[inline]
     pub fn set_display(&mut self, v: longhands::display::computed_value::T) {
@@ -1630,25 +1629,6 @@ fn static_assert() {
         self.copy_transition_property_from(other)
     }
 
-    // Hand-written because the Mako helpers transform `Preserve3d` into `PRESERVE3D`.
-    pub fn set_transform_style(&mut self, v: TransformStyle) {
-        self.gecko.mTransformStyle = match v {
-            TransformStyle::Flat => structs::NS_STYLE_TRANSFORM_STYLE_FLAT as u8,
-            TransformStyle::Preserve3d => structs::NS_STYLE_TRANSFORM_STYLE_PRESERVE_3D as u8,
-        };
-    }
-
-    // Hand-written because the Mako helpers transform `Preserve3d` into `PRESERVE3D`.
-    pub fn clone_transform_style(&self) -> TransformStyle {
-        match self.gecko.mTransformStyle as u32 {
-            structs::NS_STYLE_TRANSFORM_STYLE_FLAT => TransformStyle::Flat,
-            structs::NS_STYLE_TRANSFORM_STYLE_PRESERVE_3D => TransformStyle::Preserve3d,
-            _ => panic!("illegal transform style"),
-        }
-    }
-
-    ${impl_simple_copy('transform_style', 'mTransformStyle')}
-
     ${impl_transition_count('property', 'Property')}
 
     pub fn animations_equals(&self, other: &Self) -> bool {

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

@@ -592,7 +592,7 @@ ${helpers.single_keyword(
 ${helpers.predefined_type(
     "transform-style",
     "TransformStyle",
-    "computed::TransformStyle::" + ("Flat" if engine == "gecko" else "Auto"),
+    "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",

components/style/values/generics/transform.rs

@@ -820,9 +820,8 @@ pub use self::GenericTranslate as Translate;
     ToResolvedValue,
     ToShmem,
 )]
+#[repr(u8)]
 pub enum TransformStyle {
-    #[cfg(feature = "servo")]
-    Auto,
     Flat,
     #[css(keyword = "preserve-3d")]
     Preserve3d,