Issue 26051. Fix for MethodDeclartion.beginToken for external.

pkg/analyzer/lib/src/generated/testing/ast_factory.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.
 
 library analyzer.src.generated.testing.ast_factory;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
@@ skipping 851 matching lines @@
           null,
           modifier == null ? null : TokenFactory.tokenFromKeyword(modifier),
           returnType,
           property == null ? null : TokenFactory.tokenFromKeyword(property),
           operator == null ? null : TokenFactory.tokenFromKeyword(operator),
           name,
           typeParameters,
           parameters,
           body);
 
+  static MethodDeclaration methodDeclaration4(
+          {bool external: false,
+          Keyword modifier,
+          TypeName returnType,
+          Keyword property,
+          bool operator: false,
+          String name,
+          FormalParameterList parameters,
+          FunctionBody body}) =>
+      new MethodDeclaration(
+          null,
+          null,
+          external ? TokenFactory.tokenFromKeyword(Keyword.EXTERNAL) : null,
+          modifier == null ? null : TokenFactory.tokenFromKeyword(modifier),
+          returnType,
+          property == null ? null : TokenFactory.tokenFromKeyword(property),
+          operator ? TokenFactory.tokenFromKeyword(Keyword.OPERATOR) : null,
+          identifier3(name),
+          null,
+          parameters,
+          body);
+
   static MethodInvocation methodInvocation(Expression target, String methodName,
           [List<Expression> arguments,
           TokenType operator = TokenType.PERIOD]) =>
       new MethodInvocation(
           target,
           target == null ? null : TokenFactory.tokenFromType(operator),
           identifier3(methodName),
           null,
           argumentList(arguments));
 
@@ skipping 381 matching lines @@
           expression,
           TokenFactory.tokenFromType(TokenType.SEMICOLON));
 
   static YieldStatement yieldStatement(Expression expression) =>
       new YieldStatement(
           TokenFactory.tokenFromTypeAndString(TokenType.IDENTIFIER, "yield"),
           null,
           expression,
           TokenFactory.tokenFromType(TokenType.SEMICOLON));
 }