add role="button" to a couple more dummy-anchor btns
Update JSZip to v2.4.0.

[ci skip]
Update Holder.js to v2.4.1.

[ci skip]
Run `grunt`.

[ci skip]
Added/removed blank lines in the docs for consitency
Sorted various lines using atom/sort-lines
Merge pull request #14841 from twbs/role-button

add role="button" to a couple more dummy-anchor btns
Merge pull request #14830 from lipis/sort

Sorted various lines using atom/sort-lines
Merge pull request #14794 from twbs/docs-libs

Update customizer libraries
Merge pull request #14829 from lipis/blank-lines

Added/removed blank lines in the docs for consitency
Add `aria-pressed` to single toggle buttons

also includes tiny fix/clarification to two existing unit tests for the
.active class, adding data-toggle=“button” explicitly to the tested
buttons

Closes #14819.
grunt
Fixes tooltip misplacements in scrollable viewports with auto positioning

Fixes #14756.
Closes #14767.
Follow-up to e2cfbd5: Fix spaces in placement calculation
grunt
Implement `hide` and `hidden` events for tabs

Closes #14772.
Fix IE8 unit test breakage introduced by #14767