Auto merge of #13570 - Wafflespeanut:font_stretch, r=Manishearth

Add support for 'font-stretch' in geckolib

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

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build-geckolib` does not report any errors
- [x] `./mach test-tidy` does not report any errors

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

r? @Manishearth

<!-- 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/13570)
<!-- Reviewable:end -->

1 files changed, 20 insertions, 2 deletions

diff --git a/components/style/properties/gecko.mako.rs b/components/style/properties/gecko.mako.rs
index 99f6c0cdda3..acc3ee86fa6 100644
--- a/components/style/properties/gecko.mako.rs
+++ b/components/style/properties/gecko.mako.rs
@@ -447,7 +447,7 @@ impl Debug for ${style_struct.gecko_struct_name} {
     # These are currently being shuffled to a different style struct on the gecko side.
     force_stub += ["backface-visibility", "transform-box", "transform-style"]
     # These live in an nsFont member in Gecko. Should be straightforward to do manually.
-    force_stub += ["font-kerning", "font-stretch", "font-variant"]
+    force_stub += ["font-kerning", "font-variant"]
     # These have unusual representations in gecko.
     force_stub += ["list-style-type", "text-overflow"]
     # In a nsTArray, have to be done manually, but probably not too much work
@@ -739,7 +739,7 @@ fn static_assert() {
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="Font"
-    skip_longhands="font-family font-style font-size font-weight"
+    skip_longhands="font-family font-stretch font-style font-size font-weight"
     skip_additionals="*">
 
     pub fn set_font_family(&mut self, v: longhands::font_family::computed_value::T) {
@@ -790,6 +790,24 @@ fn static_assert() {
         Au(self.gecko.mSize)
     }
 
+    pub fn set_font_stretch(&mut self, v: longhands::font_stretch::computed_value::T) {
+        use computed_values::font_stretch::T;
+
+        self.gecko.mFont.stretch = match v {
+            T::normal => structs::NS_FONT_STRETCH_NORMAL as i16,
+            T::ultra_condensed => structs::NS_FONT_STRETCH_ULTRA_CONDENSED as i16,
+            T::extra_condensed => structs::NS_FONT_STRETCH_EXTRA_CONDENSED as i16,
+            T::condensed => structs::NS_FONT_STRETCH_CONDENSED as i16,
+            T::semi_condensed => structs::NS_FONT_STRETCH_SEMI_CONDENSED as i16,
+            T::semi_expanded => structs::NS_FONT_STRETCH_SEMI_EXPANDED as i16,
+            T::expanded => structs::NS_FONT_STRETCH_EXPANDED as i16,
+            T::extra_expanded => structs::NS_FONT_STRETCH_EXTRA_EXPANDED as i16,
+            T::ultra_expanded => structs::NS_FONT_STRETCH_ULTRA_EXPANDED as i16,
+        };
+    }
+
+    ${impl_simple_copy('font_stretch', 'mFont.stretch')}
+
     pub fn set_font_weight(&mut self, v: longhands::font_weight::computed_value::T) {
         self.gecko.mFont.weight = v as u16;
     }