anchor.diff:  
       // This call can modify [_importedDeferredBy] and [_constantsDeferredBy].
       _collectAllElementsAndConstantsResolvedFrom(
  -        element, dependentElements, constants);
  +        element, dependentElements, constants, isMirrorUsage);
   
       LibraryElement library = element.library;
       for (Element dependency in dependentElements) {
  
positive.code:       // So we have to filter them out here.
        if (element is AnalyzableElementX && !element.hasTreeElements) return;
        if (compiler.backend.isNeededForReflection(element)) {
          _mapDependencies(element, deferredImport);
        }
      }
  
  
negative.code:   void _collectAllElementsAndConstantsResolvedFrom(
        Element element,
        Set<Element> elements,
        Set<Constant> constants,
        isMirrorUsage) {
  
      /// Recursively add the constant and its dependencies to [constants].
      void addConstants(Constant constant) {
  