Since certain `prefName` values are already being handled as special cases, can't you just call `this._codeMirror.setOption(cmOptions[prefName], newValue);` in the else case? Something like:

```
            if (prefName === USE_TAB_CHAR) {
                this._codeMirror.setOption("indentUnit", newValue === true ?
                                           this._currentOptions[TAB_SIZE] :
                                           this._currentOptions[SPACE_UNITS]
                                          );
            } else if (prefName === TAB_SIZE || prefName === SPACE_UNITS) {
                this._codeMirror.setOption("indentUnit", newValue);
            } else {
                this._codeMirror.setOption(cmOptions[prefName], newValue);
            }
```