style: Implement scroll-padding parser and serializer.

Differential Revision: https://phabricator.services.mozilla.com/D20103

components/style/cbindgen.toml

@@ -78,6 +78,7 @@ include = [
   "LengthPercentage",
   "NonNegativeLengthPercentage",
   "LengthPercentageOrAuto",
+  "NonNegativeLengthPercentageOrAuto",
   "Rect",
   "IntersectionObserverRootMargin",
   "Size",

components/style/properties/gecko.mako.rs

@@ -1677,14 +1677,17 @@ fn static_assert() {
     % endfor
 </%self:impl_trait>
 
+<% skip_scroll_padding_longhands = " ".join(["scroll-padding-%s" % x.ident for x in SIDES]) %>
 <% skip_padding_longhands = " ".join(["padding-%s" % x.ident for x in SIDES]) %>
 <%self:impl_trait style_struct_name="Padding"
-                  skip_longhands="${skip_padding_longhands}">
+                  skip_longhands="${skip_padding_longhands}
+                                  ${skip_scroll_padding_longhands}">
 
     % for side in SIDES:
     <% impl_split_style_coord("padding_%s" % side.ident,
                               "mPadding",
                               side.index) %>
+    <% impl_split_style_coord("scroll_padding_%s" % side.ident, "mScrollPadding", side.index) %>
     % endfor
 </%self:impl_trait>
 

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

@@ -28,3 +28,17 @@
         servo_restyle_damage="reflow rebuild_and_reflow_inline"
     )}
 % endfor
+
+% for side in ALL_SIDES:
+    ${helpers.predefined_type(
+        "scroll-padding-%s" % side[0],
+        "NonNegativeLengthPercentageOrAuto",
+        "computed::NonNegativeLengthPercentageOrAuto::auto()",
+        products="gecko",
+        gecko_pref="layout.css.scroll-snap-v1.enabled",
+        logical=side[1],
+        logical_group="scroll-padding",
+        spec="https://drafts.csswg.org/css-scroll-snap-1/#propdef-scroll-padding-%s" % side[0],
+        animation_value_type="ComputedValue",
+    )}
+% endfor

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

@@ -27,3 +27,33 @@ ${helpers.two_properties_shorthand(
     "specified::NonNegativeLengthPercentage::parse",
     spec="https://drafts.csswg.org/css-logical/#propdef-padding-inline"
 )}
+
+${helpers.four_sides_shorthand(
+    "scroll-padding",
+    "scroll-padding-%s",
+    "specified::NonNegativeLengthPercentageOrAuto::parse",
+    products="gecko",
+    gecko_pref="layout.css.scroll-snap-v1.enabled",
+    spec="https://drafts.csswg.org/css-scroll-snap-1/#propdef-scroll-padding"
+)}
+
+${helpers.two_properties_shorthand(
+    "scroll-padding-block",
+    "scroll-padding-block-start",
+    "scroll-padding-block-end",
+    "specified::NonNegativeLengthPercentageOrAuto::parse",
+    products="gecko",
+    gecko_pref="layout.css.scroll-snap-v1.enabled",
+    spec="https://drafts.csswg.org/css-scroll-snap-1/#propdef-scroll-padding-block"
+)}
+
+${helpers.two_properties_shorthand(
+    "scroll-padding-inline",
+    "scroll-padding-inline-start",
+    "scroll-padding-inline-end",
+    "specified::NonNegativeLengthPercentageOrAuto::parse",
+    products="gecko",
+    gecko_pref="layout.css.scroll-snap-v1.enabled",
+    spec="https://drafts.csswg.org/css-scroll-snap-1/#propdef-scroll-padding-inline"
+)}
+

components/style/values/computed/length.rs

@@ -503,7 +503,7 @@ impl LengthPercentageOrAuto {
 
 /// A wrapper of LengthPercentageOrAuto, whose value must be >= 0.
 pub type NonNegativeLengthPercentageOrAuto =
-    generics::LengthPercentageOrAuto<NonNegativeLengthPercentage>;
+    generics::GenericLengthPercentageOrAuto<NonNegativeLengthPercentage>;
 
 impl NonNegativeLengthPercentageOrAuto {
     computed_length_percentage_or_auto!(NonNegativeLengthPercentage);