ActionList: Take items with css propery display:contents into account

For example, the elements of icingadb/hostgroup are `display:contents`, which leads to scrollIntoView() having no effect.

asset/js/widget/ActionList.js

@@ -14,6 +14,8 @@ define(["../notjQuery"], function ($) {
             this.lastActivatedItemUrl = null;
             this.lastTimeoutId = null;
             this.processing = false;
+
+            this.isDisplayContents = null;
         }
 
         bind() {
@@ -402,6 +404,19 @@ define(["../notjQuery"], function ($) {
          * @param pressedKey Pressed key (`ArrowUp` or `ArrowDown`)
          */
         scrollItemIntoView(item, pressedKey) {
+            if  (this.isDisplayContents
+                || (! item.checkVisibility() && item.firstChild && item.firstChild.checkVisibility())
+            ) {
+                // it's a pseudo item: display:contents, because the child is visible
+                this.isDisplayContents = true;
+                item.firstChild.scrollIntoView({block: "nearest"});
+                let directionalNext = this.getDirectionalNext(item, pressedKey);
+
+                if (directionalNext) {
+                    directionalNext.firstChild.scrollIntoView({block: "nearest"});
+                }
+            }
+
             item.scrollIntoView({block: "nearest"});
             let directionalNext = this.getDirectionalNext(item, pressedKey);