QmlDesigner: Remove dead code

Change-Id: If0eb4e662a50d2bb6b1a44649b73bd3c517dba48
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/qmldesigner/qmldesignerplugin.cpp

@@ -138,11 +138,6 @@ static bool warningsForQmlFilesInsteadOfUiQmlEnabled()
     return DesignerSettings::getValue(DesignerSettingsKey::WARNING_FOR_QML_FILES_INSTEAD_OF_UIQML_FILES).toBool();
 }
 
-static bool showWarningsForFeaturesInDesigner()
-{
-    return DesignerSettings::getValue(DesignerSettingsKey::WARNING_FOR_FEATURES_IN_DESIGNER).toBool();
-}
-
 QmlDesignerPlugin::QmlDesignerPlugin()
 {
     m_instance = this;