style: Add 'overflow-anchor' CSS property.

https://drafts.csswg.org/css-scroll-anchoring/#exclusion-api

Differential Revision: https://phabricator.services.mozilla.com/D13265

components/style/cbindgen.toml

@@ -63,6 +63,7 @@ include = [
   "Float",
   "OverscrollBehavior",
   "ScrollSnapType",
+  "OverflowAnchor",
   "OverflowClipBox",
   "Resize",
   "Overflow",

components/style/properties/data.py

@@ -326,6 +326,7 @@ class Longhand(object):
                 "Opacity",
                 "OutlineStyle",
                 "Overflow",
+                "OverflowAnchor",
                 "OverflowClipBox",
                 "OverflowWrap",
                 "OverscrollBehavior",

components/style/properties/gecko.mako.rs

@@ -1419,6 +1419,7 @@ impl Clone for ${style_struct.gecko_struct_name} {
         "Number": impl_simple,
         "Opacity": impl_simple,
         "OverflowWrap": impl_simple,
+        "OverflowAnchor": impl_simple,
         "Perspective": impl_style_coord,
         "Position": impl_position,
         "RGBAColor": impl_rgba_color,

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

@@ -125,6 +125,18 @@ ${helpers.predefined_type(
     servo_restyle_damage = "reflow",
 )}
 
+${helpers.predefined_type(
+    "overflow-anchor",
+    "OverflowAnchor",
+    "computed::OverflowAnchor::Auto",
+    initial_specified_value="specified::OverflowAnchor::Auto",
+    products="gecko",
+    needs_context=False,
+    gecko_pref="layout.css.scroll-anchoring.enabled",
+    spec="https://drafts.csswg.org/css-scroll-anchoring/#exclusion-api",
+    animation_value_type="discrete",
+)}
+
 <% transition_extra_prefixes = "moz:layout.css.prefixes.transitions webkit" %>
 
 ${helpers.predefined_type(

components/style/values/computed/box.rs

@@ -13,7 +13,7 @@ use crate::values::specified::box_ as specified;
 
 pub use crate::values::specified::box_::{AnimationName, Appearance, BreakBetween, BreakWithin};
 pub use crate::values::specified::box_::{Clear as SpecifiedClear, Float as SpecifiedFloat};
-pub use crate::values::specified::box_::{Contain, Display, Overflow, OverflowClipBox};
+pub use crate::values::specified::box_::{Contain, Display, Overflow, OverflowAnchor, OverflowClipBox};
 pub use crate::values::specified::box_::{OverscrollBehavior, ScrollSnapType};
 pub use crate::values::specified::box_::{TouchAction, TransitionProperty, WillChange};
 

components/style/values/computed/mod.rs

@@ -43,7 +43,7 @@ pub use self::border::{BorderImageRepeat, BorderImageSideWidth};
 pub use self::border::{BorderImageSlice, BorderImageWidth};
 pub use self::box_::{AnimationIterationCount, AnimationName, Contain};
 pub use self::box_::{Appearance, BreakBetween, BreakWithin, Clear, Float};
-pub use self::box_::{Display, Overflow, TransitionProperty};
+pub use self::box_::{Display, Overflow, OverflowAnchor, TransitionProperty};
 pub use self::box_::{OverflowClipBox, OverscrollBehavior, Perspective, Resize};
 pub use self::box_::{ScrollSnapType, TouchAction, VerticalAlign, WillChange};
 pub use self::color::{Color, ColorPropertyValue, RGBAColor};

components/style/values/specified/box.rs

@@ -413,6 +413,26 @@ pub enum OverscrollBehavior {
     None,
 }
 
+#[allow(missing_docs)]
+#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
+#[derive(
+    Clone,
+    Copy,
+    Debug,
+    Eq,
+    MallocSizeOf,
+    Parse,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+)]
+#[repr(u8)]
+pub enum OverflowAnchor {
+    Auto,
+    None,
+}
+
 #[allow(missing_docs)]
 #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
 #[derive(

components/style/values/specified/mod.rs

@@ -36,7 +36,7 @@ pub use self::border::{BorderCornerRadius, BorderImageSlice, BorderImageWidth};
 pub use self::border::{BorderImageRepeat, BorderImageSideWidth};
 pub use self::border::{BorderRadius, BorderSideWidth, BorderSpacing, BorderStyle};
 pub use self::box_::{AnimationIterationCount, AnimationName, Contain, Display};
-pub use self::box_::{Appearance, BreakBetween, BreakWithin, Clear, Float, Overflow};
+pub use self::box_::{Appearance, BreakBetween, BreakWithin, Clear, Float, Overflow, OverflowAnchor};
 pub use self::box_::{OverflowClipBox, OverscrollBehavior, Perspective, Resize};
 pub use self::box_::{ScrollSnapType, TouchAction, TransitionProperty, VerticalAlign, WillChange};
 pub use self::color::{Color, ColorPropertyValue, RGBAColor};