Auto merge of #14227 - chenpighead:font-size-adjust-gecko, r=Manishearth

Stylo - gecko glue code for font-size-adjust.

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

Implement the gecko-side glue code for font-size-adjust.
This is a followup for #14125, which is originally filed in #13875.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/style/properties/gecko.mako.rs

@@ -887,7 +887,7 @@ fn static_assert() {
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="Font"
-    skip_longhands="font-family font-size font-weight font-synthesis"
+    skip_longhands="font-family font-size font-size-adjust font-weight font-synthesis"
     skip_additionals="*">
 
     pub fn set_font_family(&mut self, v: longhands::font_family::computed_value::T) {
@@ -974,6 +974,28 @@ fn static_assert() {
         self.gecko.mFont.synthesis = other.gecko.mFont.synthesis;
     }
 
+    pub fn set_font_size_adjust(&mut self, v: longhands::font_size_adjust::computed_value::T) {
+        use properties::longhands::font_size_adjust::computed_value::T;
+        match v {
+            T::None => self.gecko.mFont.sizeAdjust = -1.0 as f32,
+            T::Number(n) => self.gecko.mFont.sizeAdjust = n.0 as f32,
+        }
+    }
+
+    pub fn copy_font_size_adjust_from(&mut self, other: &Self) {
+        self.gecko.mFont.sizeAdjust = other.gecko.mFont.sizeAdjust;
+    }
+
+    pub fn clone_font_size_adjust(&self) -> longhands::font_size_adjust::computed_value::T {
+        use properties::longhands::font_size_adjust::computed_value::T;
+        use values::specified::Number;
+
+        match self.gecko.mFont.sizeAdjust {
+            -1.0 => T::None,
+            _ => T::Number(Number(self.gecko.mFont.sizeAdjust)),
+        }
+    }
+
 </%self:impl_trait>
 
 <% skip_box_longhands= """display overflow-y vertical-align

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

@@ -353,16 +353,15 @@ ${helpers.single_keyword("font-variant",
 </%helpers:longhand>
 
 // https://www.w3.org/TR/css-fonts-3/#font-size-adjust-prop
-// FIXME: This prop should be animatable
-<%helpers:longhand products="none" name="font-size-adjust" animatable="False">
+<%helpers:longhand products="gecko" name="font-size-adjust" animatable="True">
     use values::NoViewportPercentage;
     use values::computed::ComputedValueAsSpecified;
     use values::specified::Number;
 
     impl ComputedValueAsSpecified for SpecifiedValue {}
     impl NoViewportPercentage for SpecifiedValue {}
 
-    #[derive(Clone, Debug, PartialEq)]
+    #[derive(Copy, Clone, Debug, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         None,
@@ -372,6 +371,8 @@ ${helpers.single_keyword("font-variant",
     pub mod computed_value {
         use style_traits::ToCss;
         use std::fmt;
+        use properties::animated_properties::Interpolate;
+        use values::specified::Number;
 
         pub use super::SpecifiedValue as T;
 
@@ -383,6 +384,16 @@ ${helpers.single_keyword("font-variant",
                 }
             }
         }
+
+        impl Interpolate for T {
+            fn interpolate(&self, other: &Self, time: f64) -> Result<Self, ()> {
+                match (*self, *other) {
+                    (T::Number(ref number), T::Number(ref other)) =>
+                        Ok(T::Number(Number(try!(number.0.interpolate(&other.0, time))))),
+                    _ => Err(()),
+                }
+            }
+        }
     }
 
     #[inline] pub fn get_initial_value() -> computed_value::T {