Minor tweak to the pubspec.lock output to remove the leading whitespace from the file.

utils/pub/lock_file.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.
 
 library lock_file;
 
 import 'dart:json' as json;
 import 'io.dart';
 import 'package.dart';
 import 'source_registry.dart';
@@ skipping 79 matching lines @@
     packages.forEach((name, id) {
       packagesObj[name] = {
         'version': id.version.toString(),
         'source': id.source.name,
         'description': id.description
       };
     });
 
     // TODO(nweiz): Serialize using the YAML library once it supports
     // serialization. For now, we use JSON, since it's a subset of YAML anyway.
-    return '''
-        # Generated by pub. See: http://pub.dartlang.org/doc/glossary.html#lockfile
-         ${json.stringify({'packages': packagesObj})}
-        ''';
+    return
+        '# Generated by pub\n'
+        '# See http://pub.dartlang.org/doc/glossary.html#lockfile\n'
+        '\n'
+        '${json.stringify({'packages': packagesObj})}\n';
   }
 }