Improve the detection lockfile freshness.

lib/src/package_graph.dart

 // Copyright (c) 2013, 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 pub.package_graph;
 
 import 'barback/transformer_cache.dart';
 import 'entrypoint.dart';
 import 'lock_file.dart';
 import 'package.dart';
@@ skipping 35 matching lines @@
       SolveResult result) {
     var packages = new Map.fromIterable(result.packages,
         key: (id) => id.name,
         value: (id) {
       if (id.name == entrypoint.root.name) return entrypoint.root;
 
       return new Package(result.pubspecs[id.name],
           entrypoint.cache.sources[id.source].getDirectory(id));
     });
 
-    return new PackageGraph(
-        entrypoint,
-        new LockFile(result.packages, entrypoint.cache.sources),
-        packages);
+    return new PackageGraph(entrypoint, result.lockFile, packages);
   }
 
   /// Loads the transformer cache for this graph.
   ///
   /// This may only be called if [entrypoint] represents a physical package.
   /// This may modify the cache.
   TransformerCache loadTransformerCache() {
     if (_transformerCache == null) {
       if (entrypoint.root.dir == null) {
         throw new StateError("Can't load the transformer cache for virtual "
@@ skipping 85 matching lines @@
   bool isPackageStatic(String package) {
     var id = lockFile.packages[package];
     if (id == null) return false;
 
     var source = entrypoint.cache.sources[id.source];
     if (source is! CachedSource) return false;
 
     return packages[package].pubspec.transformers.isEmpty;
   }
 }