style: Fix a few initial values in Rust property definitions.

Differential Revision: https://phabricator.services.mozilla.com/D67929

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

@@ -35,8 +35,8 @@ ${helpers.predefined_type(
     ${helpers.predefined_type(
         "background-position-" + axis,
         "position::" + direction + "Position",
+        "computed::LengthPercentage::zero_percent()",
         engines="gecko servo-2013 servo-2020",
-        initial_value="computed::LengthPercentage::zero()",
         initial_specified_value="SpecifiedValue::initial_specified_value()",
         spec="https://drafts.csswg.org/css-backgrounds-4/#propdef-background-position-" + axis,
         animation_value_type="ComputedValue",

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

@@ -230,7 +230,7 @@ ${helpers.predefined_type(
 ${helpers.predefined_type(
     "-moz-script-level",
     "MozScriptLevel",
-    0,
+    "0",
     engines="gecko",
     animation_value_type="none",
     enabled_in="ua",

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

@@ -245,7 +245,7 @@ ${helpers.predefined_type(
 ${helpers.predefined_type(
     "text-emphasis-style",
     "TextEmphasisStyle",
-    None,
+    "computed::TextEmphasisStyle::None",
     engines="gecko",
     initial_specified_value="SpecifiedValue::None",
     animation_value_type="discrete",
@@ -368,13 +368,12 @@ ${helpers.single_keyword(
     servo_restyle_damage="rebuild_and_reflow",
 )}
 
-// FIXME Firefox expects the initial value of this property to change depending
-// on the value of the layout.css.control-characters.visible pref.
 ${helpers.single_keyword(
     "-moz-control-character-visibility",
     "hidden visible",
     engines="gecko",
     gecko_enum_prefix="StyleControlCharacterVisibility",
+    gecko_pref_controlled_initial_value="layout.css.control-characters.visible=visible",
     animation_value_type="none",
     gecko_ffi_name="mControlCharacterVisibility",
     spec="Nonstandard",

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

@@ -333,7 +333,7 @@ ${helpers.single_keyword(
 ${helpers.predefined_type(
     "object-position",
     "Position",
-    "computed::Position::zero()",
+    "computed::Position::center()",
     engines="gecko",
     boxed=True,
     spec="https://drafts.csswg.org/css-images-3/#the-object-position",

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

@@ -111,7 +111,7 @@ ${helpers.predefined_type(
     ${helpers.predefined_type(
         "mask-position-" + axis,
         "position::" + direction + "Position",
-        "computed::LengthPercentage::zero()",
+        "computed::LengthPercentage::zero_percent()",
         engines="gecko",
         extra_prefixes="webkit",
         initial_specified_value="specified::PositionComponent::Center",

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

@@ -56,7 +56,7 @@ ${helpers.single_keyword(
 
 ${helpers.single_keyword(
     "-moz-window-shadow",
-    "none default menu tooltip sheet",
+    "default none menu tooltip sheet",
     engines="gecko",
     gecko_ffi_name="mWindowShadow",
     gecko_enum_prefix="StyleWindowShadow",

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

@@ -64,10 +64,12 @@ ${helpers.single_keyword(
     spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/box-pack)",
 )}
 
+// NOTE(heycam): Odd that the initial value is 1 yet 0 is a valid value. There
+// are uses of `-moz-box-ordinal-group: 0` in the tree, too.
 ${helpers.predefined_type(
     "-moz-box-ordinal-group",
     "Integer",
-    "0",
+    "1",
     engines="gecko",
     parse_method="parse_non_negative",
     alias="-webkit-box-ordinal-group",

components/style/values/computed/length_percentage.rs

@@ -193,6 +193,12 @@ impl LengthPercentage {
         Self::new_length(Length::new(1.))
     }
 
+    /// 0%
+    #[inline]
+    pub fn zero_percent() -> Self {
+        Self::new_percent(Percentage::zero())
+    }
+
     fn to_calc_node(&self) -> Cow<CalcNode> {
         match self.unpack() {
             Unpacked::Length(l) => Cow::Owned(CalcNode::Leaf(CalcLengthPercentageLeaf::Length(l))),