Auto merge of #22133 - servo:extern-crate, r=SimonSapin

Use 2018-edition idioms in crates that use that edition

The first commit is almost entirely mechanical, created by running `cargo fix --edition-idioms` and relevant crates. I undid the change of adding an anonymous lifetime parameter in types that have implicit lifetimes parameters, for example replacing `&mut Formatter` with `&mut Formatter<'_>`, because I don’t like it. The remaining changes are, in many places:

* Add `dyn` to trait object types, for example `Rc<gl::Gl>` to `Rc<dyn gl::Gl>`. This change also works in the 2015 edition.
* Remove `extern crate` where is it made unneeded by changes to the import/module system.

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/22133)
<!-- Reviewable:end -->

1 files changed, 0 insertions, 15 deletions

diff --git a/components/canvas/lib.rs b/components/canvas/lib.rs
index 2e42b7e1902..ab785a5620c 100644
--- a/components/canvas/lib.rs
+++ b/components/canvas/lib.rs
@@ -4,23 +4,8 @@
 
 #![deny(unsafe_code)]
 
-extern crate azure;
-extern crate canvas_traits;
-extern crate compositing;
-extern crate cssparser;
-extern crate euclid;
-extern crate fnv;
-extern crate gleam;
-extern crate ipc_channel;
 #[macro_use]
 extern crate log;
-extern crate num_traits;
-extern crate offscreen_gl_context;
-extern crate pixels;
-extern crate serde_bytes;
-extern crate servo_config;
-extern crate webrender;
-extern crate webrender_api;
 
 pub mod canvas_data;
 pub mod canvas_paint_thread;