hgweb: optimize process_dates function
This function looped over every node due to getElementsByTagName('*'), instead
of using selectors. In this patch we use querySelectorAll('.age') and process
only these nodes, which is much faster and also doesn't require extra condition.
Browser compatibility isn't sacrificed: IE 8+, FF 3.5+, Opera 10+.
Greg Ward, author of the original bfiles extension
Na'Tosha Bard of Unity Technologies
Fog Creek Software
Special thanks to the University of Toronto and the UCOSP program