[Piglit] HTML generation enhancements

[Dylan Baker]

This seies is puleed from a branch Ken Graunke has on his freedesktop
accoutn, with a few bug fixes from me. These lay the ground work for some
additional HTML generation work I'm doing, but make a very signifcant
impact on performance (in a positive way) that I thought it would be
usefull to land them ahead of my own work.

This series is available on my github account here:
git://github.com/crymson/piglit.git html-fixup-ken