[WebProfilerBundle] Fix assignment to constant variable

Resources/views/Profiler/base_js.html.twig

@@ -75,7 +75,7 @@
                     }
 
                     tab.addEventListener('click', function(e) {
-                        const activeTab = e.target || e.srcElement;
+                        let activeTab = e.target || e.srcElement;
 
                         /* needed because when the tab contains HTML contents, user can click */
                         /* on any of those elements instead of their parent '<button>' element */