the file extension/ezjscore/lib/jsmin.php is quite old (version 1.1.1 from 2008-03-02), and should be overridden by last version (2.1.3 from 2011-01-19), which is:
http://code.google.com/p/minify/source/browse/trunk/min/lib/JSMin.php

The new version of JSMin.php adds several very important features:

• Comments containing IE conditional compilation are preserved, as are multi-line
• comments that begin with "/*!" (for documentation purposes). In the latter case
• newlines are inserted around the comment to enhance readability.

I'm using the last version into ezjscore with no problem encountered...

Upgrade should be easy (just copy new file), as method to use it is the same: JSMin::minify()