To me, there are enough differences with prior versions of Safari and Safari 9 that a [safari-9] tag is worthwhile.
I've merged the safari versions all into safari. There's simply not enough traffic to warrant a specific tag for that when we can search for safari 9 in the body of posts.
If it keeps popping up, I'll probably make a synonym so that people realize that we're keeping the safari questions together for now.
I created the tag. I am mainly a chrome user so I don't know the difference. Please feel free to make the tag edit. It could however be later turned into a tag synonym to [safari]