message: [test] Tighten up a dictionary test
  This test isn't stringent enough.
  It looks like DICT: key = 4 can match, then DICT: key = 3 can match, all before
  "x[3] = 5" happens.
  rdar://38459944
diff: @@ -38,10 +38,12 @@ var x = $R0
  x.updateValue(8, forKey : 4)
  x
  +// DICT-LABEL: $R5: [Int : Int] = 4 key/value pairs
  // DICT: key = 4
  // DICT-NEXT: value = 8
  x[3] = 5
  x
  +// DICT-LABEL: $R6: [Int : Int] = 4 key/value pairs
  // DICT: key = 3
  // DICT-NEXT: value = 5
  