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

pkg/analyzer/lib/src/task/dart.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 analyzer.src.task.dart;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_resolution_map.dart';
@@ skipping 1600 matching lines @@
             }
           }
           if (entryPoint == null) {
             entryPoint = _findEntryPoint(partElement);
           }
           directive.element = partElement;
           sourcedCompilationUnits.add(partElement);
         }
       }
     }
-    if (hasPartDirective && libraryNameNode == null) {
+    if (hasPartDirective && libraryNameNode == null &&
+        !context.analysisOptions.enableUriInPartOf) {

[Brian Wilkerson, 2017/01/25 17:05:14]

Will we issue a warning if a part file contains a part-of directive that uses a
library name when the library doesn't have a name? (I'm assuming that's still an
error.)

[Lasse Reichstein Nielsen, 2017/01/26 10:39:13]

It's still a warning, and I don't think there is a warning in that case.
I didn't find the place to change for that (I'm assuming there is a warning
somewhere if the names don't match, and this should just be the same thing - the
non-empty part-of name doesn't match the empty library name).

       AnalysisError error;
       if (partsLibraryName != _UNKNOWN_LIBRARY_NAME &&
           partsLibraryName != null) {
         error = new AnalysisErrorWithProperties(librarySource, 0, 0,
             ResolverErrorCode.MISSING_LIBRARY_DIRECTIVE_WITH_PART)
           ..setProperty(ErrorProperty.PARTS_LIBRARY_NAME, partsLibraryName);
       } else {
         error = new AnalysisError(librarySource, 0, 0,
             ResolverErrorCode.MISSING_LIBRARY_DIRECTIVE_WITH_PART);
       }
@@ skipping 4919 matching lines @@
 
   @override
   bool moveNext() {
     if (_newSources.isEmpty) {
       return false;
     }
     currentTarget = _newSources.removeLast();
     return true;
   }
 }