fix positioning of active tab indicator (#695)

src/components/tab-group/tab-group.ts

@@ -297,7 +297,7 @@ export default class SlTabGroup extends LitElement {
 
     // offsetLeft/offsetTop cannot be used directly here due to a shadow parent issue: https://bugs.chromium.org/p/chromium/issues/detail?id=920069
     // neither can getBoundingClientRect as it gives invalid values for animating elements
-    const allTabs = this.getAllTabs();
+    const allTabs = this.getAllTabs(true);
     const precedingTabs = allTabs.slice(0, allTabs.indexOf(currentTab));
     const offset = precedingTabs.reduce(
       (previous, current) => ({