Bug 1795797 - If a CalDAV sync response says there are more items, request the items. r=mkmelin

Differential Revision: https://phabricator.services.mozilla.com/D159553

--HG--
extra : rebase_source : 84e2233422c85041668a788e842920a96b8b2113
extra : amend_source : 3d7d2017e89d5df78bade151a44a5025db754d02

calendar/providers/caldav/modules/CalDavRequestHandlers.jsm

@@ -569,7 +569,7 @@ class CalDavWebDavSyncHandler extends XMLResponseHandler {
       return;
     }
 
-    if (this.calendar.mWebdavSyncToken == null) {
+    if (this.calendar.mWebdavSyncToken == null && !this.additionalSyncNeeded) {
       // null token means reset or first refresh indicating we did
       // a full sync; remove local items that were not returned in this full
       // sync
@@ -597,6 +597,16 @@ class CalDavWebDavSyncHandler extends XMLResponseHandler {
         this.calendar.mWebdavSyncToken = this.newSyncToken;
         this.calendar.saveCalendarProperties();
         cal.LOG("CalDAV: New webdav-sync Token: " + this.calendar.mWebdavSyncToken);
+
+        if (this.additionalSyncNeeded) {
+          let wds = new CalDavWebDavSyncHandler(
+            this.calendar,
+            this.baseUri,
+            this.changeLogListener
+          );
+          wds.doWebDAVSync();
+          return;
+        }
       }
       this.calendar.finalizeUpdatedItems(this.changeLogListener, this.baseUri);
     }