- improves checkboxes alignment on the "Plugins" page table in the responsive view
- improves spacing between form controls on the "Add Plugins" page in the responsive view
- the layout of the "filter bar" on the "Add Plugins" page is now based on CSS Flexbox
- removes italic type from a paragraph in the "Favorites" page
Props passoniate, garethgillman, maxpertici, audrasjb, sabernhardt, afercia.
See #47327.
Fixes#49231.
Built from https://develop.svn.wordpress.org/trunk@48281
git-svn-id: http://core.svn.wordpress.org/trunk@48050 1a063a9b-81f0-0310-95a4-ce76da25c4cd