MOBILE-3320 tabs: Improve number of tabs calculation

src/core/classes/tabs.ts

@@ -378,9 +378,14 @@ export class CoreTabsBaseComponent<T extends CoreTabBase> implements OnInit, Aft
         }
 
         this.maxSlides = 3;
-        const width = this.slidesSwiper.width;
+        let width = this.slidesSwiper.width;
         if (!width) {
-            return;
+            this.slidesSwiper.updateSize();
+            width = this.slidesSwiper.width;
+
+            if (!width) {
+                return;
+            }
         }
 
         const zoomLevel = await CoreSettingsHelper.getZoom();

src/core/components/tabs-outlet/core-tabs-outlet.html

@@ -11,7 +11,6 @@
                     <ng-container *ngFor="let tab of tabs">
                         <ion-slide
                             role="presentation"
-                            [hidden]="!hideUntil"
                             [id]="tab.id! + '-tab'"
                             class="tab-slide"
                             tabindex="-1"