Make Analyzer, VM and dart2js accept URI strings as part-of library identifier.

pkg/analyzer/lib/src/generated/engine.dart

 // Copyright (c) 2014, 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 analyzer.src.generated.engine;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:typed_data';
 
@@ skipping 1404 matching lines @@
    * some analysis context.
    */
   List<ErrorProcessor> _errorProcessors;
 
   /**
    * A list of exclude patterns used to exclude some sources from analysis.
    */
   List<String> _excludePatterns;
 
   @override
-  bool enableUriInPartOf = false;
+  bool enableUriInPartOf = true;
 
   @override
   bool generateImplicitErrors = true;
 
   @override
   bool generateSdkErrors = false;
 
   @override
   bool hint = true;
 
@@ skipping 243 matching lines @@
 
   @override
   void resetToDefaults() {
     dart2jsHint = false;
     disableCacheFlushing = false;
     enableAssertInitializer = false;
     enableLazyAssignmentOperators = false;
     enableStrictCallChecks = false;
     enableSuperMixins = false;
     enableTiming = false;
-    enableUriInPartOf = false;
+    enableUriInPartOf = true;
     _errorProcessors = null;
     _excludePatterns = null;
     finerGrainedInvalidation = false;
     generateImplicitErrors = true;
     generateSdkErrors = false;
     hint = true;
     implicitCasts = true;
     implicitDynamic = true;
     incremental = false;
     incrementalApi = false;
@@ skipping 1189 matching lines @@
    */
   bool get wereSourcesAdded => _changeSet.addedSources.length > 0;
 
   /**
    * Return `true` if any sources were removed or deleted.
    */
   bool get wereSourcesRemoved =>
       _changeSet.removedSources.length > 0 ||
       _changeSet.removedContainers.length > 0;
 }