One part (of 8!) of css font family disambiguation is that font families should
be matched case-insensitively.
This patch implements that. Once it lands, a bug needs to be filed to do lowercasing
properly (as a string, instead of char-by-char -- it's a unicode thing).
r? @gw
matching, and use it for `<input size>` and `<td width>`.
This implements a general framework for legacy presentational attributes
to the DOM and style calculation, so that adding more of them later will
be straightforward.