Preserving BWC for Plugins using Dashicon's Icon Font

[grayghostvisuals]

I've been looking around to see what's being used by plugins and so far this is what I've found…

note: Using All in One SEO and W3 Total Cache plugin as the case studies

markup in use for admin menu:

<div class="wp-menu-image dashicons-before dashicons-admin-generic"></div>

styling selectors in use for admin menu

.dashicons
.dashicons-before
.dashicons-before:before
.dashicons-admin-generic
.wp-menu-image
#adminmenu div.wp-menu-image:before