The only difference between the icon that was removed and the one kept is that the removed one has a default fill color in the SVG. This meant everywhere the icon was replaced, we have to make sure that a fill color is defined in CSS. In a few cases, that necessitated adding a new class. In a few others, colors were already being defined for the icon, so there was no need to add any here. Differential Revision: https://phabricator.services.mozilla.com/D121030