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, 5 insertions, 5 deletions

diff --git a/components/layout/multicol.rs b/components/layout/multicol.rs
index 71d9befac61..0d2a72a7b3b 100644
--- a/components/layout/multicol.rs
+++ b/components/layout/multicol.rs
@@ -241,7 +241,7 @@ impl Flow for MulticolFlow {
 
     fn iterate_through_fragment_border_boxes(
         &self,
-        iterator: &mut FragmentBorderBoxIterator,
+        iterator: &mut dyn FragmentBorderBoxIterator,
         level: i32,
         stacking_context_position: &Point2D<Au>,
     ) {
@@ -252,7 +252,7 @@ impl Flow for MulticolFlow {
         );
     }
 
-    fn mutate_fragments(&mut self, mutator: &mut FnMut(&mut Fragment)) {
+    fn mutate_fragments(&mut self, mutator: &mut dyn FnMut(&mut Fragment)) {
         self.block_flow.mutate_fragments(mutator);
     }
 
@@ -295,7 +295,7 @@ impl Flow for MulticolColumnFlow {
         &mut self,
         layout_context: &LayoutContext,
         fragmentation_context: Option<FragmentationContext>,
-    ) -> Option<Arc<Flow>> {
+    ) -> Option<Arc<dyn Flow>> {
         Flow::fragment(&mut self.block_flow, layout_context, fragmentation_context)
     }
 
@@ -345,7 +345,7 @@ impl Flow for MulticolColumnFlow {
 
     fn iterate_through_fragment_border_boxes(
         &self,
-        iterator: &mut FragmentBorderBoxIterator,
+        iterator: &mut dyn FragmentBorderBoxIterator,
         level: i32,
         stacking_context_position: &Point2D<Au>,
     ) {
@@ -356,7 +356,7 @@ impl Flow for MulticolColumnFlow {
         );
     }
 
-    fn mutate_fragments(&mut self, mutator: &mut FnMut(&mut Fragment)) {
+    fn mutate_fragments(&mut self, mutator: &mut dyn FnMut(&mut Fragment)) {
         self.block_flow.mutate_fragments(mutator);
     }