Merge pull request #7 from ircmaxell/returntypehinting

Workaround for opcache clearing symbol table
remove check from ZEND_YIELD
Merge pull request #8 from ircmaxell/returntypehinting

Add comment explaining rationale for removing instanceof and going with ...
Merge branch 'returntypehinting' of github.com:krakjoe/php-src into returntypehinting