Store library paths relative to a given application root folder.

pkg/kernel/test/frontend_bench.dart

 // Copyright (c) 2016, 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.
 
 import 'dart:io';
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/task/model.dart';
 import 'package:args/args.dart';
 import 'package:kernel/analyzer/loader.dart';
 import 'package:kernel/kernel.dart';
@@ skipping 27 matching lines @@
   if (options.rest.length != 1) {
     print('Exactly one file must be given');
     exit(1);
   }
 
   String sdk = options['sdk'];
   String packagePath = options['packages'];
   bool strongMode = options['strong'];
 
   String path = options.rest.single;
+  var uri = new Uri(scheme: 'file', path: new File(path).absolute.path);
   var packages =
       getPackagesDirectory(new Uri(scheme: 'file', path: packagePath));
   Repository repository = new Repository();
 
   new DartLoader(
           repository,
           new DartOptions(
               strongMode: strongMode, sdk: sdk, packagePath: packagePath),
           packages)
-      .loadProgram(path);
+      .loadProgram(uri);
 
   CacheEntry.recomputedCounts.forEach((key, value) {
     print('Recomputed $key $value times');
   });
 
   AnalysisTask.stopwatchMap.forEach((key, Stopwatch watch) {
     print('$key took ${watch.elapsedMilliseconds} ms');
   });
 }