Add an AST factory method for fieldDeclaration with all optional named parameters.

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

 // Copyright (c) 2016, 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.
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
 import 'package:front_end/src/scanner/token.dart';
 import 'package:meta/meta.dart';
 
 /**
@@ skipping 394 matching lines @@
   /**
    * Returns a newly created field declaration. Either or both of the
    * [comment] and [metadata] can be `null` if the declaration does not have the
    * corresponding attribute. The [staticKeyword] can be `null` if the field is
    * not a static field.
    */
   FieldDeclaration fieldDeclaration(Comment comment, List<Annotation> metadata,
       Token staticKeyword, VariableDeclarationList fieldList, Token semicolon);
 
   /**
+   * Returns a newly created field declaration. Either or both of the
+   * [comment] and [metadata] can be `null` if the declaration does not have the
+   * corresponding attribute. The [staticKeyword] can be `null` if the field is
+   * not a static field.
+   */
+  FieldDeclaration fieldDeclaration2(
+      {Comment comment,
+      List<Annotation> metadata,
+      Token covariantKeyword,
+      Token staticKeyword,
+      @required VariableDeclarationList fieldList,
+      @required Token semicolon});
+
+  /**
    * Returns a newly created formal parameter. Either or both of the
    * [comment] and [metadata] can be `null` if the parameter does not have the
    * corresponding attribute. The [keyword] can be `null` if there is a type.
    * The [type] must be `null` if the keyword is 'var'. The [thisKeyword] and
    * [period] can be `null` if the keyword 'this' was not provided.  The
    * [parameters] can be `null` if this is not a function-typed field formal
    * parameter.
    */
   FieldFormalParameter fieldFormalParameter(
       Comment comment,
@@ skipping 662 matching lines @@
    */
   WithClause withClause(Token withKeyword, List<TypeName> mixinTypes);
 
   /**
    * Returns a newly created yield expression. The [star] can be `null` if no
    * star was provided.
    */
   YieldStatement yieldStatement(
       Token yieldKeyword, Token star, Expression expression, Token semicolon);
 }