servo: Merge #17488 - Replace iterator struct with anonymous return iterator type (from frewsxcv:frewsxcv-return-node-list); r=jdm

```
hi servo. it's been
some time. here's a pull request.
i hope you like it.
```

Source-Repo: https://github.com/servo/servo
Source-Revision: bc5e8f89fff9bf1922638b3eb2f4c75148dcad1e

UltraBlame original commit: c7135a797d59d6ba87ec006f902c13140ad05f2e

Author: marco-c

servo/components/script/dom/nodelist.rs

@@ -777,23 +777,61 @@ list
 pub
 fn
 iter
+<
+'
+a
+>
 (
 &
+'
+a
 self
 )
 -
 >
-NodeListIterator
-{
-NodeListIterator
+impl
+Iterator
+<
+Item
+=
+Root
+<
+Node
+>
+>
++
+'
+a
 {
-nodes
-:
+let
+len
+=
 self
-offset
-:
+.
+Length
+(
+)
+;
+(
 0
-}
+.
+.
+len
+)
+.
+flat_map
+(
+move
+|
+i
+|
+self
+.
+Item
+(
+i
+)
+)
 }
 }
 #
@@ -1908,86 +1946,3 @@ set
 ;
 }
 }
-pub
-struct
-NodeListIterator
-<
-'
-a
->
-{
-nodes
-:
-&
-'
-a
-NodeList
-offset
-:
-u32
-}
-impl
-<
-'
-a
->
-Iterator
-for
-NodeListIterator
-<
-'
-a
->
-{
-type
-Item
-=
-Root
-<
-Node
->
-;
-fn
-next
-(
-&
-mut
-self
-)
--
->
-Option
-<
-Root
-<
-Node
->
->
-{
-let
-result
-=
-self
-.
-nodes
-.
-Item
-(
-self
-.
-offset
-)
-;
-self
-.
-offset
-=
-self
-.
-offset
-+
-1
-;
-result
-}
-}