style: Add a ValueInfo trait for exposing types needed by devtools.

Most of types just derive it using proc_macro directly. Some of value
types need manual impl.

In my current plan, this new trait will be used in bug 1434130 to expose
values as well.

Bug: 1455576
Reviewed-by: emilio
MozReview-Commit-ID: LI7fy45VkRw

1 files changed, 7 insertions, 0 deletions

diff --git a/components/style_derive/lib.rs b/components/style_derive/lib.rs
index e9d799fe9a9..86442070ca1 100644
--- a/components/style_derive/lib.rs
+++ b/components/style_derive/lib.rs
@@ -16,6 +16,7 @@ mod animate;
 mod cg;
 mod compute_squared_distance;
 mod parse;
+mod specified_value_info;
 mod to_animated_value;
 mod to_animated_zero;
 mod to_computed_value;
@@ -62,3 +63,9 @@ pub fn derive_to_css(stream: TokenStream) -> TokenStream {
     let input = syn::parse(stream).unwrap();
     to_css::derive(input).into()
 }
+
+#[proc_macro_derive(SpecifiedValueInfo, attributes(css))]
+pub fn derive_specified_value_info(stream: TokenStream) -> TokenStream {
+    let input = syn::parse(stream).unwrap();
+    specified_value_info::derive(input).into()
+}