Update inherited prop state for animation

`AnimationValue` has its own path for conversion to computed values, so we need
to update `for_non_inherited_property` in the context to match the property
being converted.

I didn't notice any other generic conversions, so hopefully this is the only
missing path.

MozReview-Commit-ID: HskrpMctmYE

components/style/properties/helpers/animated_properties.mako.rs

@@ -576,6 +576,12 @@ impl AnimationValue {
             % for prop in data.longhands:
             % if prop.animatable:
             PropertyDeclaration::${prop.camel_case}(ref val) => {
+                context.for_non_inherited_property =
+                    % if prop.style_struct.inherited:
+                        None;
+                    % else:
+                        Some(LonghandId::${prop.camel_case});
+                    % endif
             % if prop.ident in SYSTEM_FONT_LONGHANDS and product == "gecko":
                 if let Some(sf) = val.get_system() {
                     longhands::system_font::resolve_system_font(sf, context);