anchor.diff:        Uri mapUri, partUri;
         Uri sourceMapUri = compiler.sourceMapUri;
         Uri outputUri = compiler.outputUri;
  +      String partName = "$hunkPrefix.$partExtension";
  +      String hunkFileName = "$hunkPrefix.$deferredExtension";
   
         if (sourceMapUri != null) {
  -        String mapFileName =
  -            hunkPrefix + deferredExtension + ".map";
  +        String mapFileName = hunkFileName + ".map";
           List<String> mapSegments = sourceMapUri.pathSegments.toList();
           mapSegments[mapSegments.length - 1] = mapFileName;
           mapUri = compiler.sourceMapUri.replace(pathSegments: mapSegments);
         }
   
         if (outputUri != null) {
  -        String hunkFileName = hunkPrefix + deferredExtension;
           List<String> partSegments = outputUri.pathSegments.toList();
           partSegments[partSegments.length - 1] = hunkFileName;
           partUri = compiler.outputUri.replace(pathSegments: partSegments);
  
positive.code: 
      if (shouldGenerateSourceMap) {
        outputSourceMap(mainOutput, lineColumnCollector, '',
        compiler.sourceMapUri, compiler.outputUri);
      }
    }
  
  
negative.code: 
        output.add(generateSourceMapTag(mapUri, partUri));
        output.close();
        outputSourceMap(output, lineColumnCollector, partName, mapUri, partUri);
      } else {
        output.close();
      }
  