Perform src/Nullable.php

productivity increased from 3 to 4 times.

Nullable::getBaseType($scalar) 60000 calls

Xdebug off

before	after
0.1097	0.0306
0.1118	0.0291
0.1136	0.0291
0.1148	0.0300
0.1168	0.0295

Xdebug on

before	after
0.6204	0.1174
0.6301	0.1188
0.6256	0.1214
0.6366	0.1214
0.6258	0.1143