servo: Merge #15715 - Make #[dom_struct] a proc_macro attribute (from nox:custom-derive); r=SimonSapin

The rustup is needed for https://github.com/rust-lang/rust/pull/40039.

Source-Repo: https://github.com/servo/servo
Source-Revision: a204c4176dcccdad8ec99d74055c66794c3f64ba

servo/components/script/dom/characterdata.rs

@@ -19,6 +19,7 @@ use dom::element::Element;
 use dom::node::{Node, NodeDamage};
 use dom::processinginstruction::ProcessingInstruction;
 use dom::text::Text;
+use dom_struct::dom_struct;
 use servo_config::opts;
 use std::cell::Ref;