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 +14,14 @@ define(["../notjQuery"], function ($) {
             this.lastActivatedItemUrl = null;
             this.lastTimeoutId = null;
             this.processing = false;
+            this.isDisplayContents = false;
+
+            let firstItem = this.getDirectionalNext(null, false);
+            if (firstItem
+                && (! firstItem.checkVisibility() && firstItem.firstChild && firstItem.firstChild.checkVisibility())
+            ) {
+                this.isDisplayContents = true;
+            }
         }
 
         bind() {
@@ -406,9 +414,13 @@ define(["../notjQuery"], function ($) {
          * @param isArrowUp Whether the arrow up key is pressed, if not, arrow down key is assumed
          */
         scrollItemIntoView(item, isArrowUp) {
-            item.scrollIntoView({block: "nearest"});
             let directionalNext = this.getDirectionalNext(item, isArrowUp);
+            if (this.isDisplayContents) {
+                item = item.firstChild;
+                directionalNext = directionalNext ? directionalNext.firstChild : null;
+            }
 
+            item.scrollIntoView({block: "nearest"});
             if (directionalNext) {
                 directionalNext.scrollIntoView({block: "nearest"});
             }