style: Switch to the new scroll-snap-type syntax for the old scroll snap implementation and drop the scroll-snap-type-{x,y} longhands.

Now scroll-snap-type is a longhand property.

Differential Revision: https://phabricator.services.mozilla.com/D21622

components/style/properties/data.py

@@ -341,7 +341,9 @@ class Longhand(object):
                 "SVGOpacity",
                 "SVGPaintOrder",
                 "ScrollSnapAlign",
+                "ScrollSnapAxis",
                 "ScrollSnapStrictness",
+                "ScrollSnapType",
                 "TextAlign",
                 "TextDecorationLine",
                 "TextEmphasisPosition",

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

@@ -427,18 +427,15 @@ ${helpers.predefined_type(
     animation_value_type="discrete",
 )}
 
-% for axis in ["x", "y"]:
-    ${helpers.predefined_type(
-        "scroll-snap-type-" + axis,
-        "ScrollSnapStrictness",
-        "computed::ScrollSnapStrictness::None",
-        products="gecko",
-        needs_context=False,
-        gecko_pref="layout.css.scroll-snap.enabled",
-        spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/scroll-snap-type-x)",
-        animation_value_type="discrete",
-    )}
-% endfor
+${helpers.predefined_type(
+    "scroll-snap-type",
+    "ScrollSnapType",
+    "computed::ScrollSnapType::none()",
+    products="gecko",
+    gecko_pref="layout.css.scroll-snap.enabled",
+    spec="https://drafts.csswg.org/css-scroll-snap-1/#scroll-snap-type",
+    animation_value_type="discrete",
+)}
 
 % for axis in ["x", "y"]:
     ${helpers.predefined_type(

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

@@ -303,36 +303,6 @@ macro_rules! try_parse_one {
     }
 </%helpers:shorthand>
 
-<%helpers:shorthand name="scroll-snap-type" products="gecko"
-                    gecko_pref="layout.css.scroll-snap.enabled"
-                    sub_properties="scroll-snap-type-x scroll-snap-type-y"
-                    spec="https://drafts.csswg.org/css-scroll-snap/#propdef-scroll-snap-type">
-    use crate::properties::longhands::scroll_snap_type_x;
-
-    pub fn parse_value<'i, 't>(
-        context: &ParserContext,
-        input: &mut Parser<'i, 't>,
-    ) -> Result<Longhands, ParseError<'i>> {
-        let result = scroll_snap_type_x::parse(context, input)?;
-        Ok(expanded! {
-            scroll_snap_type_x: result,
-            scroll_snap_type_y: result,
-        })
-    }
-
-    impl<'a> ToCss for LonghandsToSerialize<'a>  {
-        // Serializes into the single keyword value if both scroll-snap-type-x and scroll-snap-type-y are same.
-        // Otherwise into an empty string. This is done to match Gecko's behaviour.
-        fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result where W: fmt::Write {
-            if self.scroll_snap_type_x == self.scroll_snap_type_y {
-                self.scroll_snap_type_x.to_css(dest)
-            } else {
-                Ok(())
-            }
-        }
-    }
-</%helpers:shorthand>
-
 ${helpers.two_properties_shorthand(
     "overscroll-behavior",
     "overscroll-behavior-x",