[swift-evolution] [Review] SE-0077 v2: Improved operator declarations

[Ben Rimmington]

<https://github.com/apple/swift-evolution/blob/master/proposals/0077-operator-precedence.md>

Alternatives:

	precedencegroup MultiplicativePrecedence : left where Self > AdditivePrecedence

	precedencegroup MultiplicativePrecedence {
	    Self > AdditivePrecedence
	    associativity : left
	}

-- Ben