Description:
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get_object_vars returns an empty array if set ArrayObject::ARRAY_AS_PROPS flag in arrayObject

Test script:
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$a = new ArrayObject;
$a->setFlags(ArrayObject::ARRAY_AS_PROPS);
$a->b = 'b';
var_dump(get_object_vars($a));

Expected result:
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array(1) { ["b"]=> string(1) "b" }

Actual result:
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array(0) { }