- Fix usage of Platform.packageRoot.

pkg/analyzer/lib/src/codegen/tools.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.
 
 /**
  * Tools for generating code in analyzer and analysis server.
  */
 library analyzer.src.codegen.tools;
 
 import 'dart:io';
@@ skipping 293 matching lines @@
       if (!target.check(pkgPath)) {
         print(
             '${target.output(pkgPath).absolute} does not have expected contents.');
         generateNeeded = true;
       }
     }
     if (generateNeeded) {
       print('Please regenerate using:');
       String executable = Platform.executable;
       String packageRoot = '';
-      if (Platform.packageRoot.isNotEmpty) {
+      if (Platform.packageRoot != null) {
         packageRoot = ' --package-root=${Platform.packageRoot}';
       }
       String generateScript =
           join(pkgPath, joinAll(posix.split(generatorRelPath)));
       print('  $executable$packageRoot $generateScript');
       exit(1);
     } else {
       print('All generated files up to date.');
     }
   }
@@ skipping 272 matching lines @@
     if (lines.last.isEmpty) {
       lines.removeLast();
       buffer.add(new dom.Text(lines.join('\n$indent') + '\n'));
       indentNeeded = true;
     } else {
       buffer.add(new dom.Text(lines.join('\n$indent')));
       indentNeeded = false;
     }
   }
 }