Let "download complete" callbacks handle any potential cleanup.
Let "download complete" callbacks handle any potential cleanup.

Fixes #1998.

Martii/greasemonkey,HasClass0/greasemonkey,Martii/greasemonkey,HasClass0/greasemonkey,Ventero/greasemonkey,the8472/greasemonkey,Ventero/greasemonkey,the8472/greasemonkey