[editing] remove the targetRange from edit events, if the targetRange si equal to the selection (#80)

This request came from Apple after the meeting had concluded. As I see it, this removes no functionality to editors, as one can simply find the range by looking at the selection, as long as everything is synchronous and the selection doesn't change before the event is being handled. So if this makes things easier for Webkit, I am fine with removing those target ranges.

Please comment if anyone has issues with this.

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/editing/issues/80