Disable 20s unittest timeout for docs_test and dartdoc_test.

sdk/lib/_internal/dartdoc/test/dartdoc_test.dart

 // Copyright (c) 2012, 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.
 
 /// Unit tests for doc.
 library dartdocTests;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:path/path.dart' as path;
 import 'package:unittest/unittest.dart';
 
 // TODO(rnystrom): Use "package:" URL (#4968).
 import '../lib/dartdoc.dart' as dd;
 import '../lib/markdown.dart';
 import 'markdown_test.dart';
 
 main() {
+  // Some tests take more than the default 20 second unittest timeout.
+  unittestConfiguration.timeout = null;
   group('isAbsolute', () {
     final doc = new dd.Dartdoc();
 
     test('returns false if there is no scheme', () {
       expect(doc.isAbsolute('index.html'), isFalse);
       expect(doc.isAbsolute('foo/index.html'), isFalse);
       expect(doc.isAbsolute('foo/bar/index.html'), isFalse);
     });
 
     test('returns true if there is a scheme', () {
@@ skipping 243 matching lines @@
   }
 }
 
 
 validateDartdocMarkdown(String description, String markdown,
     String html) {
   var dartdoc = new dd.Dartdoc();
   validate(description, markdown, html, linkResolver: dartdoc.dartdocResolver,
       inlineSyntaxes: dartdoc.dartdocSyntaxes);
 }