getExtension method
Implementation
List<String> getExtension(String key) {
  if (Platform.isMacOS) {
    return getExtensionMacos(key);
  }
  Pointer _v = gl.glGetString(EXTENSIONS);
  String _vstr = _v.cast<Utf8>().toDartString();
  List<String> _extensions = _vstr.split(" ");
  return _extensions;
}