Description:
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Using the xmlwriter::writeAttribute() method after using a xmlwriter::text() or xmlwriter::writeCData() method does not work.

Reproduce code:
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$x = new XmlWriter();
$x->openMemory();

$x->startElement("root");
$x->text("hello word");
$x->writeAttribute("foo", "bar");
$x->endElement();

$s = $x->outputMemory(true);

echo $s;

Expected result:
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<root foo="bar">hello world</root>

Actual result:
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<root>hello world</root>