Use dartfmt on Observatory code

runtime/observatory/lib/src/models/objects/library.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.
 
 part of models;
 
 abstract class LibraryRef extends ObjectRef {
   /// The name of this library.
   String get name;
 
@@ skipping 21 matching lines @@
   Iterable<ClassRef> get classes;
 
   ScriptRef get rootScript;
   String get vmName;
 }
 
 abstract class LibraryDependency {
   bool get isImport;
   bool get isDeferred;
   LibraryRef get target;
+
   /// [optional]
   String get prefix;
 }