disablenavpop: Use winow onload instead of dom ready

This code has not been working because processAllPopups does
not execute. Test the change with:
https://en.wikipedia.org/wiki/User:Prtksxna/common.js

Bug: 62952
Change-Id: I3c8b5590b89693743c85c006fc0ee0a50e8b8342
Merge "disablenavpop: Use winow onload instead of dom ready"