function unwatchPath(path, ignored, callback) {
        _nodeDomain.exec("unwatchPath", path)
            .then(callback, callback);
    }
Stop providing change notifications for the file or directory at the
given path, calling back asynchronously with a possibly null FileSystemError
string when the operation is complete.
This function needs to mirror the signature of watchPath
because of FileSystem.prototype._watchOrUnwatchEntry implementation.

@param {string} path
@param {Array<string>} ignored
@param {function(?string)=} callback