Move file_system libraries into 'analyzer'.

pkg/analysis_server/lib/src/package_uri_resolver.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 resolver.package;
 
-import 'package:analysis_server/src/resource.dart';
-import 'package:analyzer/src/generated/source_io.dart';
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/src/generated/source.dart';
 
 
 /**
  * A [UriResolver] implementation for the `package:` scheme that uses a map of
  * package names to their directories.
  */
 class PackageMapUriResolver extends UriResolver {
   /**
    * The name of the `package` scheme.
    */
@@ skipping 66 matching lines @@
     return new NonExistingSource(uri.toString(), UriKind.PACKAGE_URI);
   }
 
   /**
    * Returns `true` if [uri] is a `package` URI.
    */
   static bool isPackageUri(Uri uri) {
     return uri.scheme == PACKAGE_SCHEME;
   }
 }