ensuring mi.zones isn't clobbered

Author: pilgreen

demo/story/index.html

@@ -15,6 +15,12 @@
     <link rel="stylesheet" href="/demo/demo.css">
 
     <script type="module">
+      window.mi = {
+        zones: {
+          test: "performance"
+        }
+      }
+
       import locker from "../locker.js";
       import distributeZones from "/index.js";
 

index.js

@@ -25,7 +25,8 @@ async function distributeZones(locker) {
 
   // Add the communication bridge 
   window.mi = window.mi || {};
-  window.mi.zones = zones.getPublicAPI();
+  window.mi.zones = window.mi.zones || {};
+  window.mi.zones = Object.assign(window.mi.zones, zones.getPublicAPI());
 
   // Give the performance team a promise
   return new Promise((resolve, reject) => {