deleteFile method
Delete the file with the given path.
Implementation
void deleteFile(String path) {
var data = _pathToData[path];
if (data is! _FileData) {
throw FileSystemException(path, 'Not a file.');
}
_pathToData.remove(path);
_removeFromParentFolderData(path);
_notifyWatchers(path, ChangeType.REMOVE);
}