MapView and Map constructor order

JSAPI 4.0beta3

HTML

<link rel="stylesheet" href="https://js.arcgis.com/4.0beta3/esri/css/main.css">
<script src="https://js.arcgis.com/4.0beta3"></script>
<div class="caption">Map, then MapView:</div>
<div id="viewDiv1"></div>
<hr>
<div class="caption">MapView, then Map:</div>
<div id="viewDiv2"></div>

CSS

.esri-view {
  height: 250px;
}

.caption {
  display: inline-block;
  padding: 3px;
  margin: 3px 0;
  border: 1px solid gray;
  border-radius: 3px;
}

JavaScript

require([
    "esri/Map",
    "esri/views/MapView",
    "dojo/domReady!"
  ],
  function(Map, MapView) {
    // Map is supplied to MapView constructor
    var map = new Map({
      basemap: "streets"
    });
    var view = new MapView({
      container: "viewDiv1",
      map: map,
      scale: 50000000,
      center: [-101.17, 21.78],
      rotation: 90
    });

    // Map is supplied afterwards to MapView as a property
    var view2 = new MapView({
      container: "viewDiv2",
      map: undefined,
      scale: 50000000,
      center: [-101.17, 21.78],
      rotation: 90
    });
    var map2 = new Map({
      basemap: "streets"
    });
    view2.map = map2;
    view.map = map2;
  });