app: forgot to check for "color_differs" for breaking out of a loop

Shouldn't change anything, just be slightly faster in some cases.

app/widgets/gimptextstyleeditor.c

@@ -948,6 +948,7 @@ gimp_text_style_editor_update_idle (GimpTextStyleEditor *editor)
             }
 
           if (! any_toggle_active &&
+              color_differs       &&
               font_differs        &&
               size_differs        &&
               baseline_differs    &&