anchor.diff:        text[outputUnit] = '$unitText';
       }
   
  -    StringBuffer sb = new StringBuffer();
  +    StringBuffer sb = StringBuffer();
       for (OutputUnit outputUnit in _allOutputUnits.toList()
         ..sort((a, b) => text[a].compareTo(text[b]))) {
         sb.write('\n\n-------------------------------\n');
  
positive.code:           for (ImportEntity import in elementEnvironment.getImports(library)) {
              if (import.isDeferred) {
                _deferredImportDescriptions[import] =
                    new ImportDescription(import, library, rootLibraryUri);
                isProgramSplit = true;
              }
            }
  
negative.code: 
    /// A cache of the result of calling `computeImportDeferName` on the keys of
    /// this map.
    final Map<ImportEntity, String> _importDeferName = {};
  
    /// A mapping from classes to their import set.
    Map<ClassEntity, ImportSet> _classToSet = {};
  
    /// A mapping from members to their import set.
    Map<MemberEntity, ImportSet> _memberToSet = {};
  
    /// A mapping from local functions to their import set.
    Map<Local, ImportSet> _localFunctionToSet = {};
  
    /// A mapping from constants to their import set.
    Map<ConstantValue, ImportSet> _constantToSet = {};
  
    Iterable<ImportEntity> get _allDeferredImports =>
        _deferredImportDescriptions.keys;
  
    /// Because the token-stream is forgotten later in the program, we cache a
    /// description of each deferred import.
    final Map<ImportEntity, ImportDescription> _deferredImportDescriptions = {};
  
    /// A lattice to compactly represent multiple subsets of imports.
    ImportSetLattice importSets = ImportSetLattice();
  