[BUGFIX] GetFeatureInfo STYLES and FILTER used together

In GetFeatureInfo WMS Request, if STYLES and FILTER are used together, it's
 like FILTER is not applied.

To fix it, we check in the QgsMapLayerRegistry if the layers associated to
 QUERY_LAYERS has already created.

src/server/qgswmsserver.cpp

@@ -1492,6 +1492,11 @@ int QgsWMSServer::getFeatureInfo( QDomDocument& result, QString version )
       {
         continue;
       }
+      QgsMapLayer * registeredMapLayer = QgsMapLayerRegistry::instance()->mapLayer( currentLayer->id() );
+      if ( registeredMapLayer )
+      {
+        currentLayer = registeredMapLayer;
+      }
 
       //skip layer if not visible at current map scale
       bool useScaleConstraint = ( scaleDenominator > 0 && currentLayer->hasScaleBasedVisibility() );