Added support for layout render tests. These use expected values for the text render output from Du…

utils/testrunner/utils.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.
 
 /**
  * Read the contents of a file [fileName] into a [List] of [String]s.
  * If the file does not exist and [errorIfNoFile] is true, throw an
  * exception, else return an empty list.
  */
 List<String> getFileContents(String filename, bool errorIfNoFile) {
@@ skipping 82 matching lines @@
   if (--dirCount == 0) {
     onComplete(files);
   }
 }
 
 /** Delete a file. */
 void deleteFile(String fname) {
   var f = new File(fname);
   f.deleteSync();
 }
+
+/** Get the name of the layout render file for a test. */
+String layoutFileName(String testname) =>
+  testname.replaceAll(new RegExp('\.dart\$'), '.render');
+
+/** Check if a test is a layout render test. renders.
+ */
+bool isLayoutRenderTest(String testname) {
+  var layoutname = layoutFileName(testname);
+  var f = new File(layoutname);
+  return f.existsSync();
+}