Get rid of all the library tags.

lib/src/backend/platform_selector/ast.dart

 // Copyright (c) 2015, 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 test.backend.platform_selector.ast;
-
 import 'package:source_span/source_span.dart';
 
 import 'visitor.dart';
 
 /// The superclass of nodes in the platform selector abstract syntax tree.
 abstract class Node {
   /// The span indicating where this node came from.
   ///
   /// This is a [FileSpan] because the nodes are parsed from a single continuous
   /// string, but the string itself isn't actually a file. It might come from a
@@ skipping 113 matching lines @@
   }
 }
 
 /// Like [FileSpan.expand], except if [start] and [end] are `null` or from
 /// different files it returns `null` rather than throwing an error.
 FileSpan _expandSafe(FileSpan start, FileSpan end) {
   if (start == null || end == null) return null;
   if (start.file != end.file) return null;
   return start.expand(end);
 }