refactor(overlay): cach ev.target, #4901

Author: wnvko

projects/igniteui-angular/src/lib/services/overlay/overlay.ts

@@ -620,13 +620,14 @@ export class IgxOverlayService implements OnDestroy {
                 return;
             }
             if (info.settings.closeOnOutsideClick) {
+                const target = ev.target as any;
                 //  if the click is on the element do not close this overlay
-                if (!info.elementRef.nativeElement.contains(ev.target)) {
+                if (!info.elementRef.nativeElement.contains(target)) {
                     // if we should exclude position target check if the click is over it. If so do not close overlay
-                    const positionTarget = info.settings.positionStrategy.settings.target as any;
+                    const positionTarget = info.settings.positionStrategy.settings.target as HTMLElement;
                     let clickOnPositionTarget = false;
                     if (positionTarget) {
-                        clickOnPositionTarget = positionTarget.contains(ev.target);
+                        clickOnPositionTarget = positionTarget.contains(target);
                     }
 
                     if (!(info.settings.excludePositionTarget && clickOnPositionTarget)) {