Rely on aProgress.isLoadingDocument to decide which onLocationChange means "document-start".
Rely on aProgress.isLoadingDocument to decide which onLocationChange means "document-start".

Refs: #1103

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