This might also be a good idea.

This kills a possible attack (only possible in Chrom* after #341) where if a malicious script is executed on the page once, it can change 4chan X's settings so that it is executed every time the page loads.  This is more of a judgement call whether to include because it kills what could be thought of as a feature (user HTML in the file info).  Although I doubt many people are using this.