style: Compute column-rule-width to 0 when column-rule-style is none

Depends on D164554

Differential Revision: https://phabricator.services.mozilla.com/D164549

components/style/properties/gecko.mako.rs

@@ -1725,9 +1725,33 @@ mask-mode mask-repeat mask-clip mask-origin mask-composite mask-position-x mask-
         }
     }
 
-    <% impl_non_negative_length("column_rule_width", "mColumnRuleWidth",
+    pub fn set_column_rule_style(&mut self, v: longhands::column_rule_style::computed_value::T) {
+        self.gecko.mColumnRuleStyle = v;
+        // NB: This is needed to correctly handling the initial value of
+        // column-rule-width when colun-rule-style changes, see the
+        // update_border_${side.ident} comment for more details.
+        self.gecko.mActualColumnRuleWidth = self.gecko.mColumnRuleWidth;
+    }
+
+    pub fn copy_column_rule_style_from(&mut self, other: &Self) {
+        self.set_column_rule_style(other.gecko.mColumnRuleStyle);
+    }
+
+    pub fn reset_column_rule_style(&mut self, other: &Self) {
+        self.copy_column_rule_style_from(other)
+    }
+
+    pub fn clone_column_rule_style(&self) -> longhands::column_rule_style::computed_value::T {
+        self.gecko.mColumnRuleStyle.clone()
+    }
+
+    <% impl_non_negative_length("column_rule_width", "mActualColumnRuleWidth",
+                                inherit_from="mColumnRuleWidth",
                                 round_to_pixels=True) %>
-    ${impl_simple('column_rule_style', 'mColumnRuleStyle')}
+
+    pub fn column_rule_has_nonzero_width(&self) -> bool {
+        self.gecko.mActualColumnRuleWidth != 0
+    }
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="Counters">
@@ -2008,6 +2032,7 @@ pub fn assert_initial_values_match(data: &PerDocumentStyleData) {
                 "border-bottom-width",
                 "border-left-width",
                 "border-right-width",
+                "column-rule-width",
                 "font-family",
                 "font-size",
                 "outline-width",

components/style/style_adjuster.rs

@@ -435,9 +435,22 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
         properties::adjust_border_width(self.style);
     }
 
+    /// column-rule-style: none causes a computed column-rule-width of zero
+    /// at computed value time.
+    fn adjust_for_column_rule_width(&mut self) {
+        let column_style = self.style.get_column();
+        if !column_style.clone_column_rule_style().none_or_hidden() {
+            return;
+        }
+        if !column_style.column_rule_has_nonzero_width() {
+            return;
+        }
+        self.style.mutate_column().set_column_rule_width(crate::Zero::zero());
+    }
+
     /// outline-style: none causes a computed outline-width of zero at computed
     /// value time.
-    fn adjust_for_outline(&mut self) {
+    fn adjust_for_outline_width(&mut self) {
         let outline = self.style.get_outline();
         if !outline.clone_outline_style().none_or_hidden() {
             return;
@@ -954,7 +967,8 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
             self.adjust_for_alignment(layout_parent_style);
         }
         self.adjust_for_border_width();
-        self.adjust_for_outline();
+        self.adjust_for_column_rule_width();
+        self.adjust_for_outline_width();
         self.adjust_for_writing_mode(layout_parent_style);
         #[cfg(feature = "gecko")]
         {