Fix for NotSupportedException if AreaBreak is inside a flex container…

[IBaltaga]

Itext seem to not support PageBreak when rendering to pdf if we put it inside a Div with the display:flex style.
For example:

<div style="display:flex;">
    <p>Hello1</p>
    <div style="page-break-after:always"></div>
    <p>Hello2</p>
</div>

will thrown an exception because it will try to draw the AreaBreak.

Did a hotfix to be able to handle even the AreaBreak when parsing the elements inside the Flex container div.