Rename analyzer_experimental to analyzer.

pkg/analyzer/test/error_test.dart

 // Copyright (c) 2013, 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:unittest/unittest.dart';
 
 import 'utils.dart';
 
 void main() {
   test("a valid Dart file doesn't throw any errors", () {
@@ skipping 42 matching lines @@
   test("an error in the middle of a very long line", () {
     expect(errorsForFile('$veryLongString void foo;$veryLongString'),
         equals('Error on line 1 of test.dart: ...\n'
                '...                                                         '
                    'void foo;                                                '
                    '...\n'
                '                                                            '
                    '^^^^\n'));
   });
 }