Fix #17964 (#17997)

* Fix #17964

Some browsers are lazy when updating dom elements after transition effects. This can be fixed by reading element properties such as offsetHeight or offsetWidth. However, creating a function using the Function constructor just to access such element, results in a violation of Content Security Policy (where applied), which in turn crashes the application. This fix actually reverts to the way this was handled in v3 and should work as intended.

js/src/util.js

@@ -121,7 +121,7 @@ const Util = (($) => {
     },
 
     reflow(element) {
-      new Function('bs', 'return bs')(element.offsetHeight)
+      return element.offsetHeight
     },
 
     triggerTransitionEnd(element) {