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

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

Index: pkg/analyzer/lib/dart/ast/ast_factory.dart
diff --git a/pkg/analyzer/lib/dart/ast/ast_factory.dart b/pkg/analyzer/lib/dart/ast/ast_factory.dart
index 3e5c448c86e16b15b697c0f76228e2f2482ddddd..a713a92ed2a7c4008e871a312bdf39dbb860d4de 100644
--- a/pkg/analyzer/lib/dart/ast/ast_factory.dart
+++ b/pkg/analyzer/lib/dart/ast/ast_factory.dart
@@ -412,6 +412,20 @@ abstract class AstFactory {
       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.