chore(*): update api docs; add typing

Author: RivaIvanova

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

@@ -332,7 +332,7 @@ export class IgxOverlayService implements OnDestroy {
         info.settings = eventArgs.settings;
         this._overlayInfos.push(info);
         info.hook = this.placeElementHook(info.elementRef.nativeElement);
-        let elementRect;
+        let elementRect: DOMRect;
         // Get the element rect size before moving it into the overlay to cache its size.
         if (info.settings.cacheSize) {
             elementRect = info.elementRef.nativeElement.getBoundingClientRect();

projects/igniteui-angular/core/src/services/overlay/utilities.ts

@@ -136,7 +136,8 @@ export interface OverlaySettings {
     excludeFromOutsideClick?: HTMLElement[];
     /**
      * @hidden @internal
-     * Set if the element should retain its size when moved to the overlay.
+     * Controls whether element size is measured before (true) or after (false) moving to the overlay container.
+     * Default is true to retain element size.
      */
     cacheSize?: boolean;
 }