check-in-place-select: try to work around select2 bug on firefox mobile

When selecting select2 shows the "loading.." state for a short time there
which shifts down the result list and makes the selection select the wrong
item.

Work around that by hiding the loading indicator after fetching the data is done
and allow it again once something is selected.

packages/check-in-place-select/src/check-in-place-select.js

@@ -168,6 +168,8 @@ export class CheckInPlaceSelect extends ScopedElementsMixin(LitElement) {
                     };
                 },
                 processResults: function (data) {
+                    that.$('#check-in-place-select-dropdown').addClass('select2-bug');
+
                     that.lastResult = data;
                     let transformed = that.jsonld.transformMembers(data, checkInPlaceContext);
                     const results = [];
@@ -185,6 +187,8 @@ export class CheckInPlaceSelect extends ScopedElementsMixin(LitElement) {
                 }
             }
         }).on("select2:select", function (e) {
+            that.$('#check-in-place-select-dropdown').removeClass('select2-bug');
+
             // set custom element attributes
             const identifier = e.params.data.id;
             const maxCapacity = e.params.data.maximumPhysicalAttendeeCapacity;
@@ -356,6 +360,10 @@ export class CheckInPlaceSelect extends ScopedElementsMixin(LitElement) {
                 -webkit-appearance: none;
             }
 
+            /* https://github.com/select2/select2/issues/5457 */
+            .select2-bug .loading-results {
+                display: none !important;
+            }
             `
         ];
     }