servo: Merge #10155 - Generalize the style structs (from bholley:generalize_style_structs); r=SimonSapin

This allows geckolib to pass gecko style structs and have the style system write to them directly, provided we implement all the traits.

Source-Repo: https://github.com/servo/servo
Source-Revision: 605842f193aedc1151ab38a99c49f693c76e5cf3

servo/components/layout/query.rs

@@ -27,6 +27,7 @@ use std::sync::{Arc, Mutex};
 use string_cache::Atom;
 use style::computed_values;
 use style::logical_geometry::{WritingMode, BlockFlowDirection, InlineBaseDirection};
+use style::properties::TComputedValues;
 use style::properties::longhands::{display, position};
 use style::properties::style_structs;
 use style::selector_impl::PseudoElement;