Fix DDC errors on DDC

lib/src/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;
 
 import 'package:analyzer/analyzer.dart' show parseDirectives;
 import 'package:analyzer/src/generated/ast.dart'
     show
         AstNode,
         CompilationUnit,
         ExportDirective,
         Identifier,
         ImportDirective,
         LibraryDirective,
         PartDirective,
-        PartOfDirective;
+        PartOfDirective,
+        UriBasedDirective;
 import 'package:analyzer/src/generated/engine.dart'
     show ParseDartTask, AnalysisContext;
 import 'package:analyzer/src/generated/source.dart' show Source, SourceKind;
 import 'package:html/dom.dart' show Document, Node;
 import 'package:html/parser.dart' as html;
 import 'package:logging/logging.dart' show Logger, Level;
 import 'package:path/path.dart' as path;
 
 import 'info.dart';
 import 'options.dart';
@@ skipping 241 matching lines @@
       // changed.
       var unit = parseDirectives(contents, name: _source.fullName);
       var newImports = new Set<DartSourceNode>();
       var newExports = new Set<DartSourceNode>();
       var newParts = new Set<DartSourceNode>();
       for (var d in unit.directives) {
         // Nothing to do for parts.
         if (d is PartOfDirective) return;
         if (d is LibraryDirective) continue;
 
+        var directiveUri = (d as UriBasedDirective).uri;
+
         // `dart:core` and other similar URLs only contain a name, but it is
         // meant to be a folder when resolving relative paths from it.
         var targetUri = uri.scheme == 'dart' && uri.pathSegments.length == 1
-            ? Uri.parse('$uri/').resolve(d.uri.stringValue)
-            : uri.resolve(d.uri.stringValue);
+            ? Uri.parse('$uri/').resolve(directiveUri.stringValue)
+            : uri.resolve(directiveUri.stringValue);
         var target =
             ParseDartTask.resolveDirective(graph._context, _source, d, null);
         if (target != null) {
           if (targetUri != target.uri) print(">> ${target.uri} $targetUri");
         }
         var node = graph.nodes.putIfAbsent(
             targetUri, () => new DartSourceNode(graph, targetUri, target));
         //var node = graph.nodeFromUri(targetUri);
         if (node._source == null || !node._source.exists()) {
           _reportError(graph, 'File $targetUri not found', unit, d);
@@ skipping 219 matching lines @@
   'dart._interceptors',
   'dart._native_typed_data',
   */
 ];
 
 /// Runtime files added to applications when running in server mode.
 final runtimeFilesForServerMode = new List<String>.from(defaultRuntimeFiles)
   ..addAll(const ['messages_widget.js', 'messages.css']);
 
 final _log = new Logger('dev_compiler.dependency_graph');