Fix some issues with IE11 EME polyfill.

- We can get a 'msneedkey' event with no init data.
- Use the correct message type name.

Issue #1689

Change-Id: Ic0e54fe8331d4700971d78095b77831de2d9580b

lib/polyfill/patchedmediakeys_ms.js

@@ -517,6 +517,9 @@ shaka.polyfill.PatchedMediaKeysMs.MediaKeySession.prototype.
  */
 shaka.polyfill.PatchedMediaKeysMs.onMsNeedKey_ = function(event) {
   shaka.log.debug('PatchedMediaKeysMs.onMsNeedKey_', event);
+  if (!event.initData) {
+    return;
+  }
 
   // Alias
   const PatchedMediaKeysMs = shaka.polyfill.PatchedMediaKeysMs;
@@ -612,7 +615,7 @@ shaka.polyfill.PatchedMediaKeysMs.MediaKeySession.prototype.
   let isNew = this.keyStatuses.getStatus() == undefined;
 
   let event2 = new shaka.util.FakeEvent('message', {
-    messageType: isNew ? 'licenserequest' : 'licenserenewal',
+    messageType: isNew ? 'license-request' : 'license-renewal',
     message: event.message.buffer,
   });