Warning fixes for wxUSE_STL=1.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@21929 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/html/htmlpars.cpp

@@ -375,7 +375,7 @@ void wxHtmlParser::PopTagHandler()
     wxList::compatibility_iterator first;
 
     if ( !m_HandlersStack ||
-         (first = m_HandlersStack->GetFirst()) == NULL )
+         !(first = m_HandlersStack->GetFirst()) )
     {
         wxLogWarning(_("Warning: attempt to remove HTML tag handler from empty stack."));
         return;