Roll Observatory packages and add a roll script

packages/csslib/lib/src/css_printer.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.
 
 part of csslib.visitor;
 
 /**
  * Visitor that produces a formatted string representation of the CSS tree.
  */
 class CssPrinter extends Visitor {
@@ skipping 496 matching lines @@
 
   void visitWildcard(Wildcard node) {
     emit('*');
   }
 
   void visitDartStyleExpression(DartStyleExpression node) {
     // TODO(terry): TBD
     throw UnimplementedError;
   }
 }