anchor.diff:        return new Timer(new Duration(milliseconds: 500), () {
           // The request is received and handled by the JS proxy script injected
           // into [_webview>] by [_injectDesignerProxy].
  -        return _executeScriptInWebview('''
  -            window.postMessage({action: 'import_code', code: '$code'}, '*');
  +        return _executeScriptInWebview(r'''
  +            window.postMessage(
  +                {action: 'import_code', code: ''' + code + r'''}, '*');
           ''');
         });
       });
  
positive.code:    * properties.
     */
    Future _injectScriptIntoWebviewMainWorld(String script) {
      script = script.replaceAll('"', r'\"')
                     .replaceAll("'", r"\'")
                     .replaceAll('\n', r'\n');
      return _executeScriptInWebview(r'''
          (function() {
            var scriptTag = document.createElement('script');
            scriptTag.innerHTML = '(function() { ''' + script + r'''; })()';
            document.body.appendChild(scriptTag);
          })();
      ''');
  
negative.code:    * parse the code. If it can't, it resets the design to an empty one.
     */
    Future setCode(String code) {
      // Escape all special charachters and enclose in double-quotes.
      code = JSON.encode(code);
      // Just in case we are called too early, wait until the webview is ready.
      return _webviewReady.future.then((_) {
        // TODO(ussuri): This doesn't work without a delay:
  