Safety check our automatic context deleting. (NGLayout only)

network/module/nsNetService.cpp

@@ -609,6 +609,10 @@ static void bam_exit_routine(URL_Struct *URL_s, int status, MWContext *window_id
 extern "C" void net_ReleaseContext(MWContext *context)
 {
     if (context) {
-        free_stub_context(context);
+        if (context->modular_data) {
+            free_stub_context(context);
+        } else {
+           TRACEMSG(("net_ReleaseContext: not releasing non-modular context"));
+        }
     }
 }