Clean up code that locates SDK and SDK version.

utils/pub/system_cache.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 system_cache;
 
 import 'dart:io';
 import 'dart:async';
 
 import 'git_source.dart';
@@ skipping 25 matching lines @@
   /// The sources from which to install packages.
   final SourceRegistry sources;
 
   /// Creates a new package cache which is backed by the given directory on the
   /// user's file system.
   SystemCache(this.rootDir)
   : _pendingInstalls = new Map<PackageId, Future<Package>>(),
     sources = new SourceRegistry();
 
   /// Creates a system cache and registers the standard set of sources.
-  factory SystemCache.withSources(String rootDir, String sdkDir) {
+  factory SystemCache.withSources(String rootDir) {
     var cache = new SystemCache(rootDir);
-    cache.register(new SdkSource(sdkDir));
+    cache.register(new SdkSource());
     cache.register(new GitSource());
     cache.register(new HostedSource());
     cache.sources.setDefault('hosted');
     return cache;
   }
 
   /// Registers a new source. This source must not have the same name as a
   /// source that's already been registered.
   void register(Source source) {
     source.bind(this);
@@ skipping 32 matching lines @@
 
   /// Delete's the system cache's internal temp directory.
   Future deleteTempDir() {
     log.fine('Clean up system cache temp directory $tempDir.');
     return dirExists(tempDir).then((exists) {
       if (!exists) return new Future.immediate(null);
       return deleteDir(tempDir);
     });
   }
 }