Revert "Add NormalFormalParameter.covariantKeyword setter and factory parameter."

pkg/analyzer/lib/dart/ast/ast.dart

Index: pkg/analyzer/lib/dart/ast/ast.dart
diff --git a/pkg/analyzer/lib/dart/ast/ast.dart b/pkg/analyzer/lib/dart/ast/ast.dart
index 624f84005479d3e522ce24a8c4983dc9e4e342dd..38e477fc02b1d52ebad44d685481a8acb3826d63 100644
--- a/pkg/analyzer/lib/dart/ast/ast.dart
+++ b/pkg/analyzer/lib/dart/ast/ast.dart
@@ -5311,11 +5311,6 @@ abstract class NodeList<E extends AstNode> implements List<E> {
  */
 abstract class NormalFormalParameter extends FormalParameter {
   /**
-   * Set the token for the 'covariant' keyword to the given [token].
-   */
-  void set covariantKeyword(Token token);
-
-  /**
    * Return the documentation comment associated with this parameter, or `null`
    * if this parameter does not have a documentation comment associated with it.
    */