Description:
------------
yield-by-reference in the class method not working I how expected.



Test script:
---------------
class Test
{
    public $data = [];

    function __construct($data){
        $this->data = $data;
    }

    function &getIterator($d) {
        $this->data = $d;
        foreach ($d as $key => $value) {
            yield $key => $value;
        }
    }

    function printData()
    {
        foreach ($this->data as $key => $value) {
            echo($key . ':' . $value . PHP_EOL);
        }
    }
}

$data = array('one'=>'Curly', 'two'=>'Larry', 'three'=>'Moe');
$t = new Test($data);

foreach ($t->getIterator($data) as $key => &$value) {
    $value = strtoupper($value);
}

$t->printData();

Expected result:
----------------
I expected names in uppercase:

one:CURLY
two:LARRY
three:MOE

Actual result:
--------------
$t->printData() of the test script display:

one:Curly
two:Larry
three:Moe