chore(*): Fixing issue with ContentChildren for grid columns/row islands.

Author: MKirova

projects/igniteui-angular/src/lib/grids/columns/column-group.component.ts

@@ -164,7 +164,7 @@ export class IgxColumnGroupComponent extends IgxColumnComponent implements After
             this._headerTemplate = this.headTemplate.toArray()[0].template;
         }
         // currently only ivy fixes the issue, we have to slice only if the first child is group
-        if (this.children.first.columnGroup) {
+        if (this.children.first === this) {
             this.children.reset(this.children.toArray().slice(1));
         }
         this.children.forEach(child => {

projects/igniteui-angular/src/lib/grids/hierarchical-grid/row-island.component.ts

@@ -267,8 +267,9 @@ export class IgxRowIslandComponent extends IgxHierarchicalGridBaseDirective
     }
 
     protected updateChildren() {
-        // Delete the line below once we update to Angular 9
-        this.children.reset(this.children.toArray().slice(1));
+        if (this.children.first === this) {
+            this.children.reset(this.children.toArray().slice(1));
+        }
         this.children.forEach(child => {
             child.parentIsland = this;
         });