Auto merge of #16349 - chenpighead:stylo-initial-letter-support, r=heycam

Stylo - add glue code for initial-letter property

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

Add glue code for initial-letter property.

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

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

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/16349)
<!-- Reviewable:end -->

components/style/properties/gecko.mako.rs

@@ -3039,7 +3039,7 @@ fn static_assert() {
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="Text"
-                  skip_longhands="text-decoration-line text-overflow"
+                  skip_longhands="text-decoration-line text-overflow initial-letter"
                   skip_additionals="*">
 
     pub fn set_text_decoration_line(&mut self, v: longhands::text_decoration_line::computed_value::T) {
@@ -3120,6 +3120,29 @@ fn static_assert() {
         self.gecko.mTextOverflow.mLogicalDirections = other.gecko.mTextOverflow.mLogicalDirections;
     }
 
+    pub fn set_initial_letter(&mut self, v: longhands::initial_letter::computed_value::T) {
+        use properties::longhands::initial_letter::computed_value::T;
+        match v {
+            T::Normal => {
+                self.gecko.mInitialLetterSize = 0.;
+                self.gecko.mInitialLetterSink = 0;
+            },
+            T::Specified(size, sink) => {
+                self.gecko.mInitialLetterSize = size.value;
+                if let Some(sink) = sink {
+                    self.gecko.mInitialLetterSink = sink.value();
+                } else {
+                    self.gecko.mInitialLetterSink = size.value.floor() as i32;
+                }
+            }
+        }
+    }
+
+    pub fn copy_initial_letter_from(&mut self, other: &Self) {
+        self.gecko.mInitialLetterSize = other.gecko.mInitialLetterSize;
+        self.gecko.mInitialLetterSink = other.gecko.mInitialLetterSink;
+    }
+
     #[inline]
     pub fn has_underline(&self) -> bool {
         (self.gecko.mTextDecorationLine & (structs::NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE as u8)) != 0

components/style/properties/longhand/text.mako.rs

@@ -233,7 +233,7 @@ ${helpers.predefined_type(
 
 <%helpers:longhand name="initial-letter"
                    animation_type="none"
-                   products="none"
+                   products="gecko"
                    spec="https://drafts.csswg.org/css-inline/#sizing-drop-initials">
     use std::fmt;
     use style_traits::ToCss;