wasm: make timers work for the new event dispatcher

Don’t exit from the timer callback if there is no main
thread event dispatcher, since it could be that the main
thread event dispatcher is of the old event dispatcher type.

Pick-to: 6.2
Change-Id: Ibb7a34a99e2001b52d2a985022f5baa7cd2152bf
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

src/corelib/kernel/qeventdispatcher_wasm.cpp

@@ -526,9 +526,6 @@ void QEventDispatcherWasm::callProcessTimers(void *context)
 {
     Q_ASSERT(emscripten_is_main_runtime_thread());
 
-    // Bail out if Qt has been shut down
-    if (!g_mainThreadEventDispatcher)
-        return;
 
     // Note: "context" may be a stale pointer here,
     // take care before casting and dereferencing!