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, 10 insertions, 10 deletions

diff --git a/components/script/dom/cssrule.rs b/components/script/dom/cssrule.rs
index 51dc17d3343..65ff5393a89 100644
--- a/components/script/dom/cssrule.rs
+++ b/components/script/dom/cssrule.rs
@@ -44,25 +44,25 @@ impl CSSRule {
         }
     }
 
-    pub fn as_specific(&self) -> &SpecificCSSRule {
+    pub fn as_specific(&self) -> &dyn SpecificCSSRule {
         if let Some(rule) = self.downcast::<CSSStyleRule>() {
-            rule as &SpecificCSSRule
+            rule as &dyn SpecificCSSRule
         } else if let Some(rule) = self.downcast::<CSSFontFaceRule>() {
-            rule as &SpecificCSSRule
+            rule as &dyn SpecificCSSRule
         } else if let Some(rule) = self.downcast::<CSSKeyframesRule>() {
-            rule as &SpecificCSSRule
+            rule as &dyn SpecificCSSRule
         } else if let Some(rule) = self.downcast::<CSSMediaRule>() {
-            rule as &SpecificCSSRule
+            rule as &dyn SpecificCSSRule
         } else if let Some(rule) = self.downcast::<CSSNamespaceRule>() {
-            rule as &SpecificCSSRule
+            rule as &dyn SpecificCSSRule
         } else if let Some(rule) = self.downcast::<CSSViewportRule>() {
-            rule as &SpecificCSSRule
+            rule as &dyn SpecificCSSRule
         } else if let Some(rule) = self.downcast::<CSSKeyframeRule>() {
-            rule as &SpecificCSSRule
+            rule as &dyn SpecificCSSRule
         } else if let Some(rule) = self.downcast::<CSSImportRule>() {
-            rule as &SpecificCSSRule
+            rule as &dyn SpecificCSSRule
         } else if let Some(rule) = self.downcast::<CSSSupportsRule>() {
-            rule as &SpecificCSSRule
+            rule as &dyn SpecificCSSRule
         } else {
             unreachable!()
         }