Disable browser's own autocomplete suggestions in ComboBox (#16647)

Change-Id: I600d4c506511ed688d39b93cc6fde6c7a49a5353

client/src/com/vaadin/client/ui/VFilterSelect.java

@@ -1131,6 +1131,26 @@ public class VFilterSelect extends Composite implements Field, KeyDownHandler,
      */
     public class FilterSelectTextBox extends TextBox {
 
+        /**
+         * Creates a new filter select text box.
+         * 
+         * @since
+         */
+        public FilterSelectTextBox() {
+            /*-
+             * Stop the browser from showing its own suggestion popup.
+             * 
+             * Using an invalid value instead of "off" as suggested by
+             * https://developer.mozilla.org/en-US/docs/Web/Security/Securing_your_site/Turning_off_form_autocompletion
+             * 
+             * Leaving the non-standard Safari options autocapitalize and
+             * autocorrect untouched since those do not interfere in the same
+             * way, and they might be useful in a combo box where new items are
+             * allowed.
+             */
+            getElement().setAttribute("autocomplete", "nope");
+        }
+
         /**
          * Overridden to avoid selecting text when text input is disabled
          */