Hi Andrew,

This isn't a bug in itself, but the results make me suspicious. When we were integrating another issue, I made a mistake in conflict resolution, which casused a JS error in chooserdialogue.js.

In turn, this caused a JS error rate of like 20 errors per second, continually increasing, in chrome! It makes me suspicious why this might be occuring, and might be related to why people are seeing poor performance.

Steps to reproduce:

1. Use chrome
2. Apply attached patch
3. reset caches
4. Go to course page and turn editing on
5. Watch the error console count go up and Up and UP!