anchor.diff:      // boilerplate JS code, like the sourcemap directives or the hash
       // itself.
       Map<OutputUnit, String> deferredLoadHashes =
  -        emitDeferredOutputUnits(program);
  +        emitDeferredOutputUnits(deferredParts);
       emitMainOutputUnit(program, deferredLoadHashes);
   
       if (backend.requiresPreamble &&
  
positive.code: }""");
    }
  
    /// Returns a map from OutputUnit to a hash of its content. The hash uniquely
    /// identifies the code of the output-unit. It does not include
    /// boilerplate JS code, like the sourcemap directives or the hash
    /// itself.
    Map<OutputUnit, String> emitDeferredOutputUnits(Program program) {
      if (!program.isSplit) return const {};
  
      Map<OutputUnit, jsAst.Expression> outputs =
          new Map<OutputUnit, jsAst.Expression>();
  
  
negative.code: 
      Iterable<LibraryElement> libraries =
          task.outputLibraryLists[mainOutputUnit];
      if (libraries == null) libraries = <LibraryElement>[];
  
      List<jsAst.Expression> parts = <jsAst.Expression>[];
      for (LibraryElement library in Elements.sortedByPosition(libraries)) {
  