Description:
------------
PHP Segfaults when trying to expand an infinite operator

Test script:
---------------
$iterator = new InfiniteIterator(new ArrayIterator([0, 1, 2, 3, 4]));
var_dump(...$iterator);

echo "Still alive!";

Expected result:
----------------
Something sensible, either the script aborting to lack of memory, or otherwise shutting down cleanly.

Actual result:
--------------
Segfaults apparently https://3v4l.org/6IRrp/segfault#tabs

/usr/bin/php-7.0.0(zend_call_function+0x1c6)[0x72b196]
/usr/bin/php-7.0.0(zend_call_method+0x22e)[0x754f2e]
/usr/bin/php-7.0.0(zend_user_it_move_forward+0x37)[0x755457]
/usr/bin/php-7.0.0[0x7c5e8b]
/usr/bin/php-7.0.0(execute_ex+0x1b)[0x77617b]
/usr/bin/php-7.0.0(zend_execute+0x1a7)[0x7c7e37]
/usr/bin/php-7.0.0(zend_execute_scripts+0xb4)[0x739484]
/usr/bin/php-7.0.0(php_execute_script+0x280)[0x6dd2e0]
/usr/bin/php-7.0.0[0x7c9a54]
/usr/bin/php-7.0.0[0x434198]
/usr/lib/libc.so.6(__libc_start_main+0xf1)[0x7fd7c1dd2741]
/usr/bin/php-7.0.0(_start+0x29)[0x4342d9]