Resolve obvious deprecation warnings on bleeding edge

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.
 
 import 'dart:collection' show HashSet, HashMap;
 
 import 'package:analyzer/analyzer.dart' show parseDirectives;
-import 'package:analyzer/src/generated/ast.dart'
+import 'package:analyzer/dart/ast/ast.dart'
     show
         AstNode,
         CompilationUnit,
         ExportDirective,
         Identifier,
         ImportDirective,
         LibraryDirective,
         PartDirective,
         PartOfDirective,
         UriBasedDirective;
 import 'package:analyzer/src/generated/engine.dart' show AnalysisContext;
-import 'package:analyzer/src/task/dart.dart' show ParseDartTask;
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/source.dart' show Source, SourceKind;
+import 'package:analyzer/src/task/dart.dart' show ParseDartTask;
 import 'package:html/dom.dart' show Document, Node, Element;
 import 'package:html/parser.dart' as html;
 import 'package:logging/logging.dart' show Logger, Level;
 import 'package:path/path.dart' as path;
 
 import '../compiler.dart' show defaultRuntimeFiles;
 import '../info.dart';
 import '../options.dart';
 import '../report.dart';
 import '../report/html_reporter.dart';
@@ skipping 499 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');