servo: Merge #14358 - stylo - implement -webkit-text-fill-color and -webkit-text-stroke (from chenpighead:webkit-text-stroke); r=canaltinova

<!-- Please describe your changes on the following line: -->

Implement -webkit-text-fill-color property.
Implement -webkit-text-stroke property, along with -webkit-text-stroke-width and -webkit-text-stroke-color longhand properties.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #13849 (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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Source-Repo: https://github.com/servo/servo
Source-Revision: c4f87f451faf8eeac3e046c38ebf8b9b3dd0051e

servo/components/style/properties/gecko.mako.rs

@@ -1819,7 +1819,8 @@ fn static_assert() {
 
 
 <%self:impl_trait style_struct_name="InheritedText"
-                  skip_longhands="text-align text-emphasis-style text-shadow line-height letter-spacing word-spacing">
+                  skip_longhands="text-align text-emphasis-style text-shadow line-height letter-spacing word-spacing
+                                  -webkit-text-stroke-width">
 
     <% text_align_keyword = Keyword("text-align", "start end left right center justify -moz-center -moz-left " +
                                                   "-moz-right match-parent") %>
@@ -1966,6 +1967,13 @@ fn static_assert() {
         self.gecko.mTextEmphasisStyle = other.gecko.mTextEmphasisStyle;
     }
 
+    #[allow(non_snake_case)]
+    pub fn set__webkit_text_stroke_width(&mut self, v: longhands::_webkit_text_stroke_width::computed_value::T) {
+        self.gecko.mWebkitTextStrokeWidth.set_value(CoordDataValue::Coord(v.0));
+    }
+
+    <%call expr="impl_coord_copy('_webkit_text_stroke_width', 'mWebkitTextStrokeWidth')"></%call>
+
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="Text"

servo/components/style/properties/longhand/inherited_text.mako.rs

@@ -996,6 +996,48 @@ ${helpers.predefined_type("text-emphasis-color", "CSSColor",
                           products="gecko",animatable=True,
                           complex_color=True, need_clone=True)}
 
+// CSS Compatibility
+// https://compat.spec.whatwg.org/#the-webkit-text-fill-color
+${helpers.predefined_type(
+    "-webkit-text-fill-color", "CSSColor",
+    "CSSParserColor::CurrentColor",
+    products="gecko", animatable=True,
+    complex_color=True, need_clone=True)}
+
+// CSS Compatibility
+// https://compat.spec.whatwg.org/#the-webkit-text-stroke-color
+${helpers.predefined_type(
+    "-webkit-text-stroke-color", "CSSColor",
+    "CSSParserColor::CurrentColor",
+    products="gecko", animatable=True,
+    complex_color=True, need_clone=True)}
+
+// CSS Compatibility
+// https://compat.spec.whatwg.org/#the-webkit-text-stroke-width
+<%helpers:longhand products="gecko" name="-webkit-text-stroke-width" animatable="False">
+    use app_units::Au;
+    use std::fmt;
+    use style_traits::ToCss;
+    use values::HasViewportPercentage;
+    use values::specified::BorderWidth;
+
+    pub type SpecifiedValue = BorderWidth;
+
+    #[inline]
+    pub fn parse(_context: &ParserContext, input: &mut Parser)
+                 -> Result<SpecifiedValue, ()> {
+        BorderWidth::parse(input)
+    }
+
+    pub mod computed_value {
+        use app_units::Au;
+        pub type T = Au;
+    }
+    #[inline] pub fn get_initial_value() -> computed_value::T {
+        Au::from_px(0)
+    }
+</%helpers:longhand>
+
 // TODO(pcwalton): `full-width`
 ${helpers.single_keyword("text-transform",
                          "none capitalize uppercase lowercase",

servo/components/style/properties/shorthand/inherited_text.mako.rs

@@ -78,3 +78,58 @@
         }
     }
 </%helpers:shorthand>
+
+// CSS Compatibility
+// https://compat.spec.whatwg.org/#the-webkit-text-stroke
+<%helpers:shorthand name="-webkit-text-stroke"
+                    sub_properties="-webkit-text-stroke-color
+                                    -webkit-text-stroke-width"
+                    products="gecko">
+    use cssparser::Color as CSSParserColor;
+    use properties::longhands::{_webkit_text_stroke_color, _webkit_text_stroke_width};
+    use values::specified::CSSColor;
+
+    pub fn parse_value(context: &ParserContext, input: &mut Parser) -> Result<Longhands, ()> {
+        use values::specified::{BorderWidth, Length};
+        use app_units::Au;
+
+        let (mut color, mut width, mut any) = (None, None, false);
+        % for value in "color width".split():
+            if ${value}.is_none() {
+                if let Ok(value) = input.try(|input| _webkit_text_stroke_${value}::parse(context, input)) {
+                    ${value} = Some(value);
+                    any = true;
+                }
+            }
+        % endfor
+
+        if !any {
+            return Err(());
+        }
+
+        Ok(Longhands {
+            _webkit_text_stroke_color: color.or(Some(CSSColor { parsed: CSSParserColor::CurrentColor,
+                                                                authored: None })),
+            _webkit_text_stroke_width: width.or(Some(BorderWidth::from_length(Length::Absolute(Au::from_px(0))))),
+        })
+    }
+
+    impl<'a> LonghandsToSerialize<'a>  {
+        fn to_css_declared<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+            let mut style_present = false;
+            if let DeclaredValue::Value(ref width) = *self._webkit_text_stroke_width {
+                style_present = true;
+                try!(width.to_css(dest));
+            }
+
+            if let DeclaredValue::Value(ref color) = *self._webkit_text_stroke_color {
+                if style_present {
+                    try!(write!(dest, " "));
+                }
+                try!(color.to_css(dest));
+            }
+
+            Ok(())
+        }
+    }
+</%helpers:shorthand>