style: Implement the counter-set property.

Bug: 1518201
Reviewed-by: emilio

components/style/properties/gecko.mako.rs

@@ -4559,7 +4559,7 @@ clip-path
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="Counters"
-                  skip_longhands="content counter-increment counter-reset">
+                  skip_longhands="content counter-increment counter-reset counter-set">
     pub fn ineffective_content_property(&self) -> bool {
         self.gecko.mContents.is_empty()
     }
@@ -4788,7 +4788,7 @@ clip-path
         )
     }
 
-    % for counter_property in ["Increment", "Reset"]:
+    % for counter_property in ["Increment", "Reset", "Set"]:
         pub fn set_counter_${counter_property.lower()}(
             &mut self,
             v: longhands::counter_${counter_property.lower()}::computed_value::T

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

@@ -27,9 +27,18 @@ ${helpers.predefined_type(
 
 ${helpers.predefined_type(
     "counter-reset",
-    "CounterReset",
+    "CounterSetOrReset",
     initial_value="Default::default()",
     animation_value_type="discrete",
     spec="https://drafts.csswg.org/css-lists-3/#propdef-counter-reset",
     servo_restyle_damage="rebuild_and_reflow",
 )}
+
+${helpers.predefined_type(
+    "counter-set",
+    "CounterSetOrReset",
+    initial_value="Default::default()",
+    animation_value_type="discrete",
+    spec="https://drafts.csswg.org/css-lists-3/#propdef-counter-set",
+    servo_restyle_damage="rebuild_and_reflow",
+)}

components/style/values/computed/counters.rs

@@ -7,13 +7,13 @@
 use crate::values::computed::url::ComputedImageUrl;
 use crate::values::generics::counters as generics;
 use crate::values::generics::counters::CounterIncrement as GenericCounterIncrement;
-use crate::values::generics::counters::CounterReset as GenericCounterReset;
+use crate::values::generics::counters::CounterSetOrReset as GenericCounterSetOrReset;
 
 /// A computed value for the `counter-increment` property.
 pub type CounterIncrement = GenericCounterIncrement<i32>;
 
-/// A computed value for the `counter-increment` property.
+/// A computed value for the `counter-set` and `counter-reset` properties.
-pub type CounterReset = GenericCounterReset<i32>;
+pub type CounterSetOrReset = GenericCounterSetOrReset<i32>;
 
 /// A computed value for the `content` property.
 pub type Content = generics::Content<ComputedImageUrl>;

components/style/values/computed/mod.rs

@@ -45,7 +45,7 @@ pub use self::box_::{OverflowClipBox, OverscrollBehavior, Perspective, Resize};
 pub use self::box_::{ScrollSnapAlign, ScrollSnapType, TouchAction, VerticalAlign, WillChange};
 pub use self::color::{Color, ColorOrAuto, ColorPropertyValue, RGBAColor};
 pub use self::column::ColumnCount;
-pub use self::counters::{Content, ContentItem, CounterIncrement, CounterReset};
+pub use self::counters::{Content, ContentItem, CounterIncrement, CounterSetOrReset};
 pub use self::easing::TimingFunction;
 pub use self::effects::{BoxShadow, Filter, SimpleShadow};
 pub use self::flex::FlexBasis;

components/style/values/generics/counters.rs

@@ -45,21 +45,21 @@ impl<I> Deref for CounterIncrement<I> {
     }
 }
 
-/// A generic value for the `counter-reset` property.
+/// A generic value for the `counter-set` and `counter-reset` properties.
 #[derive(
     Clone, Debug, Default, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToComputedValue, ToCss,
 )]
-pub struct CounterReset<I>(Counters<I>);
+pub struct CounterSetOrReset<I>(Counters<I>);
 
-impl<I> CounterReset<I> {
+impl<I> CounterSetOrReset<I> {
-    /// Returns a new value for `counter-reset`.
+    /// Returns a new value for `counter-set` / `counter-reset`.
     #[inline]
     pub fn new(counters: Vec<CounterPair<I>>) -> Self {
-        CounterReset(Counters(counters.into_boxed_slice()))
+        CounterSetOrReset(Counters(counters.into_boxed_slice()))
     }
 }
 
-impl<I> Deref for CounterReset<I> {
+impl<I> Deref for CounterSetOrReset<I> {
     type Target = [CounterPair<I>];
 
     #[inline]

components/style/values/specified/counters.rs

@@ -10,7 +10,7 @@ use crate::parser::{Parse, ParserContext};
 use crate::values::generics::counters as generics;
 use crate::values::generics::counters::CounterIncrement as GenericCounterIncrement;
 use crate::values::generics::counters::CounterPair;
-use crate::values::generics::counters::CounterReset as GenericCounterReset;
+use crate::values::generics::counters::CounterSetOrReset as GenericCounterSetOrReset;
 #[cfg(feature = "gecko")]
 use crate::values::generics::CounterStyleOrNone;
 use crate::values::specified::url::SpecifiedImageUrl;
@@ -34,10 +34,10 @@ impl Parse for CounterIncrement {
     }
 }
 
-/// A specified value for the `counter-increment` property.
+/// A specified value for the `counter-set` and `counter-reset` properties.
-pub type CounterReset = GenericCounterReset<Integer>;
+pub type CounterSetOrReset = GenericCounterSetOrReset<Integer>;
 
-impl Parse for CounterReset {
+impl Parse for CounterSetOrReset {
     fn parse<'i, 't>(
         context: &ParserContext,
         input: &mut Parser<'i, 't>,

components/style/values/specified/mod.rs

@@ -44,7 +44,7 @@ pub use self::box_::{ScrollSnapAlign, ScrollSnapType};
 pub use self::box_::{TouchAction, TransitionProperty, VerticalAlign, WillChange};
 pub use self::color::{Color, ColorOrAuto, ColorPropertyValue, RGBAColor};
 pub use self::column::ColumnCount;
-pub use self::counters::{Content, ContentItem, CounterIncrement, CounterReset};
+pub use self::counters::{Content, ContentItem, CounterIncrement, CounterSetOrReset};
 pub use self::easing::TimingFunction;
 pub use self::effects::{BoxShadow, Filter, SimpleShadow};
 pub use self::flex::FlexBasis;