[wildcard-variables] Remove unnamed optional wildcards with no default. (#3938)

Author: kallentu

working/wildcards/feature-specification.md

@@ -4,7 +4,7 @@ Author: Bob Nystrom
 
 Status: In-progress
 
-Version 1.5
+Version 1.6
 
 ## Motivation
 
@@ -357,16 +357,6 @@ class B extends A {
 }
 ```
 
-### Unnamed optional parameters
-
-```dart
-int foo([int _]) => 3; // OK.
-```
-
-An optional unnamed parameter, that's not an initializing or super parameter,
-is allowed to have no default value, even if its type is non-nullable. We
-will stop producing a compile time error for this case.
-
 ### Extension types
 
 An extension type declaration has a `<representationDeclaration>`
@@ -479,6 +469,9 @@ This lint is included in the core lint set which means that the scale of the bre
 
 ## Changelog
 
+### 1.6
+- Added and removed allowing unnamed optional wildcard parameters to have no default value, even if they are non-nullable. Discussion: [language/#3807](https://github.com/dart-lang/language/issues/3807)
+
 ### 1.5
 - Allow `super._`. Discussion: [language/#3792](https://github.com/dart-lang/language/issues/3792)