Always use preserveComment: 'some'
Add white-space: nowrap; to .dropdown-header

Dropdowns adjust their width to the width of their containing a elements - which have no line breaks ([*](https://github.com/twbs/bootstrap/commit/f226463b057f945795661c3d19fbcabf63b931f7)). Consistent to this dropdown-headers also should be prevent to contain line breaks.
fixes #13021: add .form-group-sm/-lg
grunt
fixes #13020: proper color for small/.small in list group headings
fixes #13093: reset the background color and remove background image on disabled theme buttons
fix part of #13111: hide the docs nav on small and below devices
Merge pull request #13851 from ahoereth/patch-1

Add white-space: nowrap; to .dropdown-header
Merge pull request #13857 from twbs/list_group_small

List group headings and small/.small
change skew(x,y) to skewX skewY because mdn told me so
fixes #13346: add a variable for .dl-horizontal's offset
fixes #13347: make striped progress bars its own class
Fixes #13400, #13415: actually document the existing practice for links in panel headings
grunt
Merge pull request #13860 from twbs/fixes_13346

Add a variable for .dl-horizontal's offset
Merge branch 'master' of github.com:twbs/bootstrap
grunt
Merge pull request #13859 from twbs/skew_you

Change skew(x,y) to skewX skewY
Merge branch 'master' into new_striped_progress_bar_class
rewrite striped and active to deprecate the parent selectors, change the docs