Revert "Simplify nsITimer usage:"
Doesn't work in Firefox 3.6 and older

This reverts commit 6547088c51f038cfd7989bb63a29cb6e63066194.
Update Attributes Inspector: fix nsITimer usage in Firefox <= 3.6
(reverted from commit 6547088c51f038cfd7989bb63a29cb6e63066194)