pkg/docgen: moved model classes into minilibs

pkg/docgen/lib/src/package_helpers.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.
 
 library docgen.package_helpers;
 
-import '../../../../sdk/lib/_internal/compiler/implementation/mirrors/source_mirrors.dart';
+import 'exports/source_mirrors.dart';
 
 import 'dart:io';
 import 'package:path/path.dart' as path;
 import 'package:yaml/yaml.dart';
 
 /// Helper accessor to determine the full pathname of the root of the dart
 /// checkout. We can be in one of three situations:
 /// 1) Running from pkg/docgen/bin/docgen.dart
 /// 2) Running from a snapshot in a build,
 ///   e.g. xcodebuild/ReleaseIA32/dart-sdk/bin
@@ skipping 57 matching lines @@
   while (!_pubspecFor(dir).existsSync()) {
     var newDir = path.dirname(dir);
     if (newDir == dir) return null;
     dir = newDir;
   }
   return dir;
 }
 
 File _pubspecFor(String directoryName) =>
     new File(path.join(directoryName, 'pubspec.yaml'));