Description:
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Cloning and DOMDocument doesn't clone the properties

Reproduce code:
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<?php
$dom = new DOMDocument;
$dom->formatOutput = 1;
var_dump($dom->formatOutput);

$dom2 = clone $dom;
var_dump($dom2->formatOutput);


Expected result:
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bool(true)
bool(true)

Actual result:
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bool(true)
bool(false)