Missing some mozilla icons because we still loading them from "chrome://browser/skin" rather than "chrome://global/skin/icons"

I noticed that the "Onion Services Keys" prefernces dialog is missing its warning icon because it still uses "chrome://browser/skin/warning.svg" rather than "chrome://global/skin/icons/warning.svg". I'm guessing these icon paths were changed in mozilla-central. Some have been converted in our patches, but not all.