fix #14114 mo' betta
add docs note about browsers w/ JS disabled; fixes #14134

[skip sauce]
Another new js bin link

/cc @cvrebert @hnrch02
Merge pull request #14143 from twbs/fix-14134

add docs note about browsers with JS disabled
Fix jsbin link
Merge pull request #14151 from BBosman/fix-link

Fix jsbin link
Follow-up to #13907: simplify JS logic for focus shim
Merge pull request #14160 from hnrch02/simplify-button-focus-logic

Follow-up to #13907: simplify JS logic for focus shim
speed up js tests a bit
Tabs to spaces
Merge pull request #14171 from wangsai/tab2space

Tabs to spaces in variables.less
Merge pull request #14055 from twbs/fat-speed-up-tests

speed up js tests a bit