[agiow] (0) Drop drawCustomFocusRing(), since no browsers have indicated interest in implementing it, and rename drawSystemFocusRing() to drawFocusIfNeeded() to match implementations.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=27049
Affected topics: Canvas

git-svn-id: https://svn.whatwg.org/webapps@8854 340c8d12-0b0e-0410-8428-c7bf67bfef74