(i)frame based sites cause horrible performence in firefox 14.0.1

[Aryeh Friedman]

Sites that are based on frames or iframes (such as google mail and
most of google's non-search services) kill the performance of
www/firefox [firefox-14.0.1_1,1] (last updated yesterday on a 9.1
built at the same time) here is the uname:

FreeBSD XXX 9.1-PRERELEASE FreeBSD 9.1-PRERELEASE #2: Thu Aug  9
15:54:37 EDT 2012     root at XXX:/usr/obj/usr/src/sys/GENERIC  i386