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

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

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Defines the AST model. The AST (Abstract Syntax Tree) model describes the
  * syntactic (as opposed to semantic) structure of Dart code. The semantic
  * structure of the code is modeled by the
  * [element model](../element/element.dart).
  *
@@ skipping 5293 matching lines @@
  *
  *    normalFormalParameter ::=
  *        [FunctionTypedFormalParameter]
  *      | [FieldFormalParameter]
  *      | [SimpleFormalParameter]
  *
  * Clients may not extend, implement or mix-in this class.
  */
 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.
    */
   Comment get documentationComment;
 
   /**
    * Set the documentation comment associated with this parameter to the given
    * [comment].
    */
   void set documentationComment(Comment comment);
@@ skipping 1710 matching lines @@
   /**
    * Return the 'yield' keyword.
    */
   Token get yieldKeyword;
 
   /**
    * Return the 'yield' keyword to the given [token].
    */
   void set yieldKeyword(Token token);
 }