Description:
------------
As shown in the test script, when a switch statement is used on a byref variable from a foreach, the reference is lost, and it changes to byval instead. 

This regression was introduced in 7.0.5, and worked perfectly otherwise in previous builds of 7.0.x, 5.6, and HHVM

https://3v4l.org/eg1oT

Test script:
---------------
$array = ['broken'];

foreach($array as &$values) {
	switch ($values) {
		case 'broken':
			$values = 'WORKING';
		break;
	}
}

var_dump($array);

Expected result:
----------------
array(1) {
  [0]=>
  &string(7) "WORKING"
}

Actual result:
--------------
array(1) {
  [0]=>
  string(6) "broken"
}