Misc: Drop support for older browsers; update support comments

That includes IE<8, Opera 12.x, Firefox<29, Safari<6.0 and some hacks
for old Blackberry.

Fixes gh-1836
Fixes gh-1701
Refs gh-1815
Refs gh-1820
I haven't seen this form; It looks weird, it seems to suggest that it works in IE<11 but maybe in newer versions as well. I'd leave it as is.