Merge branch '8.2.x' into mkirova/fix-6411

Author: ChronosSF

projects/igniteui-angular/src/lib/directives/for-of/for_of.directive.ts

@@ -404,7 +404,8 @@ export class IgxForOfDirective<T> implements OnInit, OnChanges, DoCheck, OnDestr
             });
             const destructor = takeUntil<any>(this.destroy$);
             this.contentResizeNotify.pipe(destructor,
-            filter(() => this.igxForContainerSize && this.igxForOf && this.igxForOf.length > 0), throttleTime(40))
+            filter(() => this.igxForContainerSize && this.igxForOf && this.igxForOf.length > 0),
+             throttleTime(40, undefined, {leading: true, trailing: true}))
             .subscribe(() => {
                 this._zone.runTask(() => {
                     this.updateSizes();

projects/igniteui-angular/src/lib/grids/hierarchical-grid/hierarchical-grid.integration.spec.ts

@@ -618,7 +618,7 @@ describe('IgxHierarchicalGrid Integration #hGrid', () => {
             await wait(30);
             fixture.detectChanges();
             hierarchicalGrid.verticalScrollContainer.scrollTo(hierarchicalGrid.dataView.length - 1);
-            await wait(30);
+            await wait(100);
             fixture.detectChanges();
 
             // check last row is loaded and is in view