anchor.diff:      if (userCode != null) {
         Set<Uri> uris = new Set<Uri>.from(userCode.loader.builders.keys);
         uris.removeAll(dillLoadedData.loader.builders.keys);
  +      if (previousSourceBuilders != null) {
  +        for(Library library in previousSourceBuilders) {
  +          uris.add(library.importUri);
  +        }
  +      }
         invalidatedUris.addAll(uris);
       }
     }
  
positive.code:       new Uri(scheme: "org-dartlang-debug", path: "synthetic_debug_expression");
  
    KernelTarget userCode;
  
    IncrementalCompiler.fromComponent(
        this.context, this.componentToInitializeFrom,
  
negative.code:         userCode.loader.builders.clear();
          userCode = userCodeOld;
        } else {
          previousSourceBuilders = await convertSourceLibraryBuildersToDill();
        }
  
        // Output result.
  