anchor.diff:  
     Map builtMap;
     if (buildSourceMap && sourceMap != null) {
  -    builtMap =
  -        placeSourceMap(sourceMap.build(jsUrl), mapUrl, <String, String>{});
  +    builtMap = placeSourceMap(
  +        sourceMap.build(jsUrl), mapUrl, <String, String>{}, customScheme);
       var jsDir = path.dirname(path.fromUri(jsUrl));
       var relative = path.relative(path.fromUri(mapUrl), from: jsDir);
       var relativeMapUrl = path.toUri(relative).toString();
  
positive.code: }
  
  JSCode jsProgramToCode(JS.Program moduleTree, ModuleFormat format,
      {bool buildSourceMap: false, String jsUrl, String mapUrl}) {
    var opts = new JS.JavaScriptPrintingOptions(
        allowKeywordsInProperties: true, allowSingleLineIfStatements: true);
    var printer;
  
negative.code:   var jsCode = jsProgramToCode(jsModule, moduleFormat,
        buildSourceMap: argResults['source-map'],
        jsUrl: path.toUri(output).toString(),
        mapUrl: path.toUri(output + '.map').toString(),
        customScheme: customScheme);
    file.writeAsStringSync(jsCode.code);
  
    if (jsCode.sourceMap != null) {
  