anchor.diff:      return await runWithFrontEndContext('Compute kernel', () async {
         await _refreshInvalidatedFiles();
   
  -      CanonicalName nameRoot = new CanonicalName.root();
  -
         // Load the SDK outline before building the graph, so that the file
         // system state is configured to skip SDK libraries.
  -      await _loadSdkOutline(nameRoot);
  +      await _loadSdkOutline();
   
         // Ensure that the graph starting at the entry point is ready.
         FileState entryLibrary =
  
positive.code:       DillTarget dillTarget = new DillTarget(
            new Ticker(isVerbose: false), uriTranslator, _options.target);
  
        // If there is the SDK outline, load it.
        // Load the SDK outline before building the graph, so that the file
        // system state is configured to skip SDK libraries.
        await _loadSdkOutline(nameRoot);
        if (_sdkOutline != null) {
          dillTarget.loader.appendLibraries(_sdkOutline);
          await dillTarget.buildOutlines();
  
negative.code:     return signatureBuilder.toHex();
    }
  
    /// If SDK outline bytes are provided, and it is not loaded yet into
    /// [_sdkOutline], load it and configure the file system state to skip SDK
    /// library files.
    Future<Null> _loadSdkOutline() async {
      if (_sdkOutlineBytes != null && _sdkOutline == null) {
        await _logger.runAsync('Load SDK outline from bytes', () async {
          _sdkOutline = loadProgramFromBytes(_sdkOutlineBytes);
          // Configure the file system state to skip the outline libraries.
          for (var outlineLibrary in _sdkOutline.libraries) {
            _fsState.skipSdkLibraries.add(outlineLibrary.importUri);
  