Remove library tags, they aren't needed

lib/src/server/dependency_graph.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.
 
 /// Tracks the shape of the import/export graph and dependencies between files.
-library dev_compiler.src.dependency_graph;
 
 import 'dart:collection' show HashSet, HashMap;
 
 import 'package:analyzer/analyzer.dart' show parseDirectives;
 import 'package:analyzer/src/generated/ast.dart'
     show
         AstNode,
         CompilationUnit,
         ExportDirective,
         Identifier,
@@ skipping 502 matching lines @@
     var deps = includeParts ? node.allDeps : node.depsWithoutParts;
     deps.forEach(helper);
     action(node);
   }
   helper(start);
 }
 
 bool _same(Set a, Set b) => a.length == b.length && a.containsAll(b);
 
 final _log = new Logger('dev_compiler.dependency_graph');