fix: asynchronously destroy items evicted on clearHistory navigation (#847)

fixes #829

Author: buuhuu

Diff for: nativescript-angular/router/page-router-outlet.ts

@@ -64,6 +64,7 @@ export class PageRouterOutlet { // tslint:disable-line:directive-class-suffix
     private refCache: RefCache = new RefCache();
     private isInitialPage: boolean = true;
     private detachedLoaderFactory: ComponentFactory<DetachedLoader>;
+    private itemsToDestroy: CacheItem[] = [];
 
     private currentActivatedComp: ComponentRef<any>;
     private currentActivatedRoute: ActivatedRoute;
@@ -132,7 +133,12 @@ export class PageRouterOutlet { // tslint:disable-line:directive-class-suffix
 
     private clearRefCache() {
         while (this.refCache.length > 0) {
-            this.destroyCacheItem(this.refCache.pop());
+            this.itemsToDestroy.push(this.refCache.pop());
+        }
+    }
+    private destroyQueuedCacheItems() {
+        while (this.itemsToDestroy.length > 0) {
+            this.destroyCacheItem(this.itemsToDestroy.pop());
         }
     }
     private destroyCacheItem(poppedItem: CacheItem) {
@@ -242,7 +248,10 @@ export class PageRouterOutlet { // tslint:disable-line:directive-class-suffix
         // Add it to the new page
         page.content = componentView;
 
-        page.on("navigatedFrom", (<any>global).Zone.current.wrap((args: NavigatedData) => {
+        page.on(Page.navigatedToEvent, () => setTimeout(() => {
+            this.destroyQueuedCacheItems();
+        }));
+        page.on(Page.navigatedFromEvent, (<any>global).Zone.current.wrap((args: NavigatedData) => {
             if (args.isBackNavigation) {
                 this.locationStrategy._beginBackPageNavigation();
                 this.locationStrategy.back();