/// getSourceLine - Given a line number, return the start and end of the
/// line in the file. If the line number is invalid, or if the file could
/// not be loaded, null pointers are returned for the start and end of the
/// getSourceLine - Given a line number, return the start and end of the
/// line in the file. If the line number is invalid, or if the file could
/// not be loaded, null pointers are returned for the start and end of the