[SR-8184] Migrator not correctly migrating from "none" to empty option set

[ChristopherRogers]

Previous ID	SR-8184
Radar	None
Original Reporter	@ChristopherRogers
Type	Bug

Environment

Xcode 10.0 beta 3 (10L201y)

Additional Detail from JIRA

Votes	0
Component/s	Source Tooling
Labels	Bug, Migrator
Assignee	None
Priority	Medium

md5: 957c37bc31bd4c6e1015cf5db3b6dd98

Issue Description:

import UIKit

func enumCaseToEmptyOptionSetLiteral() {
  // error: 'none' is unavailable: use [] to construct an empty option set
  // _ = [
  //   .underlineStyle: NSNumber(value: NSUnderlineStyle.none.rawValue)
  //   ] as [NSAttributedString.Key: Any]
  _ = [
    .underlineStyle: NSNumber(value: NSUnderlineStyle.styleNone.rawValue)
  ] as [NSAttributedStringKey: Any]
}

(This also happens after removing the NSNumber initializer.)

I've attached a sample Xcode project for several issues to SR-8180.

[belkadan]

cc @nkcsgexi