anchor.diff:  
     _LibraryResynthesizer(this.summaryResynthesizer, this.linkedLibrary,
         this.unlinkedUnits, this.librarySource) {
  -    libraryUri = librarySource.uri.toString();
  -    isCoreLibrary = libraryUri == 'dart:core';
  +    libraryUri = librarySource.uri;
  +    libraryUriStr = libraryUri.toString();
  +    isCoreLibrary = libraryUriStr == 'dart:core';
     }
   
     @override
  
positive.code:     });
      // Add all the names from [exportNames].
      for (LinkedExportName exportName in exportNames) {
        definedNames.putIfAbsent(
            exportName.name, () => buildExportName(exportName));
      }
      return new Namespace(definedNames);
    }
  
negative.code:   List<String> getReferencedLocationComponents(
        int dependencyIndex, int unit, String name) {
      if (dependencyIndex == 0) {
        String partUri;
        if (unit != 0) {
          String uri = unlinkedUnits[0].publicNamespace.parts[unit - 1];
          partUri = _resolveRelativeUri(uri);
        } else {
          partUri = libraryUriStr;
        }
        return <String>[libraryUriStr, partUri, name];
      }
  
      LinkedDependency dependency = linkedLibrary.dependencies[dependencyIndex];
      String referencedLibraryUri = _resolveRelativeUri(dependency.uri);
  
      String partUri;
      if (unit != 0) {
        String uri = dependency.parts[unit - 1];
        partUri = _resolveRelativeUri(uri);
      } else {
        partUri = referencedLibraryUri;
      }
  