Replace ASSERT in FaviconManager::setIcon by return

The ASSERT in FaviconManager::setIcon can be triggered by what seems
to be a race condition. Apparently the old request can be gone (so
m_inProgressRequests.contains(id) is false), but m_inProgressRequests
can still be non-empty, because of a new request to the same URL, so
this case is not covered by checking m_inProgressRequests.isEmpty()
before.

Task-number: QTBUG-57900
Change-Id: I2f26c05e5c97e4bd8d1cea03e8005cf61f2b0c98
Reviewed-by: Michael Brüning <michael.bruning@qt.io>

src/core/favicon_manager.cpp

@@ -138,11 +138,9 @@ void FaviconManagerPrivate::storeIcon(int id, const QIcon &icon)
     Q_Q(FaviconManager);
 
     // Icon download has been interrupted
-    if (m_inProgressRequests.isEmpty())
+    if (!m_inProgressRequests.contains(id))
         return;
 
-    Q_ASSERT(m_inProgressRequests.contains(id));
-
     QUrl requestUrl = m_inProgressRequests[id];
     FaviconInfo &faviconInfo = q->m_faviconInfoMap[requestUrl];