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
Nice catch; this was added in https://github.com/jquery/jquery/commit/9ce1d09a0a002eb147411166dee800335a60f4e4; I'll patch the test as well.