Stop counting requests for 'undefined' and 'Undefined'

Requests for “undefined" and "Undefined" are fo the by
far biggest part artifacts of JavaScript issues, so we no longer
count them.

For an hour worth of 120K requests/s, this patch adds <2 seconds on my
3 year old desktop.

Bug: 66352
Change-Id: Iad629fecc1337823eea8d81cd1aa771a6021d031