style: Add an inherited internal UA sheet property (-moz-list-reversed:true|false) to propagate <ol reversed> to its relevant descendants.

Bug: 288704
Reviewed-by: emilio

components/style/cbindgen.toml

@@ -108,6 +108,7 @@ include = [
   "TouchAction",
   "WillChangeBits",
   "TextDecorationLine",
+  "MozListReversed",
 ]
 item_types = ["enums", "structs", "typedefs"]
 

components/style/properties/data.py

@@ -324,6 +324,7 @@ class Longhand(object):
                 "JustifyItems",
                 "JustifySelf",
                 "MozForceBrokenImageIcon",
+                "MozListReversed",
                 "MozScriptLevel",
                 "MozScriptMinSize",
                 "MozScriptSizeMultiplier",

components/style/properties/gecko.mako.rs

@@ -1247,6 +1247,7 @@ impl Clone for ${style_struct.gecko_struct_name} {
         "Length": impl_absolute_length,
         "LengthOrNormal": impl_style_coord,
         "LengthPercentageOrAuto": impl_style_coord,
+        "MozListReversed": impl_simple,
         "MozScriptMinSize": impl_absolute_length,
         "RGBAColor": impl_rgba_color,
         "SVGLength": impl_svg_length,

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

@@ -68,3 +68,15 @@ ${helpers.predefined_type(
     boxed=True,
     spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/-moz-image-region)",
 )}
+
+${helpers.predefined_type(
+    "-moz-list-reversed",
+    "MozListReversed",
+    "computed::MozListReversed::False",
+    animation_value_type="discrete",
+    products="gecko",
+    enabled_in="ua",
+    needs_context=False,
+    spec="Internal implementation detail for <ol reversed>",
+    servo_restyle_damage="rebuild_and_reflow",
+)}

components/style/values/computed/list.rs

@@ -6,6 +6,7 @@
 
 #[cfg(feature = "gecko")]
 pub use crate::values::specified::list::ListStyleType;
+pub use crate::values::specified::list::MozListReversed;
 pub use crate::values::specified::list::{QuotePair, Quotes};
 
 use servo_arc::Arc;

components/style/values/computed/mod.rs

@@ -64,6 +64,7 @@ pub use self::length::{LengthOrAuto, LengthPercentageOrAuto, MaxSize, Size};
 pub use self::length::{NonNegativeLengthPercentage, NonNegativeLengthPercentageOrAuto};
 #[cfg(feature = "gecko")]
 pub use self::list::ListStyleType;
+pub use self::list::MozListReversed;
 pub use self::list::{QuotePair, Quotes};
 pub use self::motion::OffsetPath;
 pub use self::outline::OutlineStyle;

components/style/values/specified/list.rs

@@ -123,3 +123,13 @@ impl Parse for Quotes {
         }
     }
 }
+
+/// Specified and computed `-moz-list-reversed` property (for UA sheets only).
+#[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, Parse, PartialEq, SpecifiedValueInfo, ToComputedValue, ToCss)]
+#[repr(u8)]
+pub enum MozListReversed {
+    /// the initial value
+    False,
+    /// exclusively used for <ol reversed> in our html.css UA sheet
+    True,
+}

components/style/values/specified/mod.rs

@@ -66,6 +66,7 @@ pub use self::length::{NoCalcLength, ViewportPercentageLength};
 pub use self::length::{NonNegativeLengthPercentage, NonNegativeLengthPercentageOrAuto};
 #[cfg(feature = "gecko")]
 pub use self::list::ListStyleType;
+pub use self::list::MozListReversed;
 pub use self::list::{QuotePair, Quotes};
 pub use self::motion::OffsetPath;
 pub use self::outline::OutlineStyle;