Fully parse function names with @ in Error.stack - #27

Function name in Error.stack can contain @ when function is defined as an
object property:

    const obj = { '@fn'() { throw new Error(); } };
    obj['@fn']();
    /*
    Exception: Error
    obj["@fn"]@Scratchpad/1:10:31
    @Scratchpad/1:11:1
    */