IFramePortlet doesn't display properly with a css based layout on IE6 and causes column wrapping

The IFramePortlet demo shown on the guest default page isn't properly displayed on IE6 when using a css based layout.
Note: Firefox doesn't have this problem!

The iframe element is rendered (from the web-content component o.a.j.portlet.IFrameGenericPortlet) with a width="100%" and height="100%".
But IE6.0 cannot handle that when it is wrapped in a div with our current css based layout.
First of all, it doesn't display any content anymore currently.
Seeminly IE cannot handle this within a div (css compliance is clearly not the strongest point of IE).
If you hardcode a width like 600px, then it shows its content again but still only one column is displayed when that "overflows" the column width.
Luckily, I found an easy fix: wrapping the iframe within an table does the trick
<table><tr><td><iframe>....</iframe></td></tr></table>

I'll update the IFrameGenericPortlet doing that.

Together with the fix for JS2-348, this should solve the current css column layout problems.