Excluded elements from <pre> tag

[Ladislav Brychta]

Hello, I came up with an interesting "bug" that the purifier deletes the contents of nested elements inside the <pre> tag. I found this in file /library/HTMLPurifier/HTMLModule/Text.php between lines 60-69, $pre->excludes..  Does anyone know why? I'm mainly interested in the tags 'big', 'small' and 'font'. HTML specification does not prohibit using of these tags inside <pre>, or does it? The mentioned tags in <pre> generally works in actual browsers and there is no reason nor for security to remove them with their content, which is probably the biggest problem.