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.

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1 files changed, 0 insertions, 2 deletions

diff --git a/components/gfx/font_cache_thread.rs b/components/gfx/font_cache_thread.rs
index 77a816db9b9..0c769aeb71a 100644
--- a/components/gfx/font_cache_thread.rs
+++ b/components/gfx/font_cache_thread.rs
@@ -12,7 +12,6 @@ use crate::platform::font_list::for_each_variation;
 use crate::platform::font_list::system_default_family;
 use crate::platform::font_list::SANS_SERIF_FONT_FAMILY;
 use crate::platform::font_template::FontTemplateData;
-use fontsan;
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
 use net_traits::request::{Destination, RequestInit};
 use net_traits::{fetch_async, CoreResourceThread, FetchResponseMsg};
@@ -25,7 +24,6 @@ use std::sync::{Arc, Mutex};
 use std::{f32, fmt, mem, thread};
 use style::font_face::{EffectiveSources, Source};
 use style::values::computed::font::FamilyName;
-use webrender_api;
 
 /// A list of font templates that make up a given font family.
 pub struct FontTemplates {