Explain better than the en_US locale is always available, fix other doc glitches.

pkg/intl/test/data_directory.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.
 
 /**
  * A utility function for test and tools that compensates (at least for very
  * simple cases) for file-dependent programs being run from different
  * directories. The important cases are
  *   -running in the directory that contains the test itself, i.e.
  *    pkg/intl/test or a sub-directory.
  *   -running in pkg/intl, which is where the editor will run things by default
  *   -running in the top-level dart directory, where the build tests run
  */
 library data_directory;
 
 import "dart:io";
 import "package:pathos/path.dart" as path;
 
 String get dataDirectory {
   return path.join(intlDirectory, datesRelativeToIntl);
 }
 
 String get intlDirectory {
   var components = path.split(path.current);
   var foundIntlDir = false;
 
   /**
    * A helper function that returns false (indicating we should stop iterating)
    * if the argument to the previous call was 'intl' and also sets
-   * the outer scope [foundIntl].
+   * the outer scope [foundIntlDir].
    */
   bool checkForIntlDir(String each) {
     if (foundIntlDir) return false;
     foundIntlDir = (each == 'intl') ? true : false;
     return true;
   }
 
   var pathUpToIntl = components.takeWhile(checkForIntlDir).toList();
   // We assume that if we're not somewhere underneath the intl hierarchy
   // that we are in the dart root.
   if (foundIntlDir) {
     return path.joinAll(pathUpToIntl);
   } else {
     if (new Directory(path.join(path.current, 'pkg', 'intl')).existsSync()) {
       return path.join(path.current, 'pkg', 'intl');
     }
     if (new Directory(
         path.join(path.current, '..', 'pkg', 'intl')).existsSync()) {
       return path.join(path.current, '..', 'pkg', 'intl');
     }
   }
   throw new UnsupportedError(
       'Cannot find ${path.join('pkg','intl')} directory.');
 }
 
 String get datesRelativeToIntl => path.join('lib', 'src', 'data', 'dates');