message: [lit] Relax NSString test by not checking the REPL welcome message, NFC
  This NSString-in-REPL test was checking the text of the REPL welcome
  message, which is a little brittle, and was broken by a change which
  added a newline.
  It seems simpler to not check the welcome text at all.
diff: import Foundation
  var aString = "patatino" as NSString
  -// NSSTRING: Welcome to Swift
  -// NSSTRING-NEXT: aString: NSTaggedPointerString = "patatino"
  +// NSSTRING: aString: NSTaggedPointerString = "patatino"
  aString.substring(to: 3)
  // NSSTRING: $R0: String = "pat"
  