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
Totally forgot about, came across this year ago or so, meant to fix it, but forgot :(((.

In shell case, as i recall, we can remove this whole `else if` since original fix - 
>  IE8-10 improperly clones children of object elements using classid.

Was not presented with tests and bug was fishy, but that "fix" generated bug #10324

I.e. i'm pretty sure we can safely remove it, i curse myself about this now :-).