chor(NativeScriptPlatformRef): Destroy lastModuleRef on exitEvent

Author: m-abs

Diff for: nativescript-angular/platform-common.ts

@@ -33,6 +33,7 @@ import {
     on,
     launchEvent,
     LaunchEventData,
+    exitEvent,
 } from "tns-core-modules/application";
 import { TextView } from "tns-core-modules/ui/text-view";
 
@@ -255,7 +256,16 @@ export class NativeScriptPlatformRef extends PlatformRef {
                 args.root = rootContent;
             }
         );
+        const exitCallback = profile(
+            "nativescript-angular/platform-common.exitCallback",() => {
+                const lastModuleRef = lastBootstrappedModule ? lastBootstrappedModule.get() : null;
+                if (lastModuleRef) {
+                    lastModuleRef.destroy();
+                }
+            }
+        );
         on(launchEvent, launchCallback);
+        on(exitEvent, exitCallback);
 
         applicationRun();
     }

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

@@ -352,12 +352,19 @@ export class PageRouterOutlet implements OnDestroy { // tslint:disable-line:dire
         // Add it to the new page
         page.content = componentView;
 
-        page.on(Page.navigatedFromEvent, (<any>global).Zone.current.wrap((args: NavigatedData) => {
+        const navigatedFromCallback = (<any>global).Zone.current.wrap((args: NavigatedData) => {
             if (args.isBackNavigation) {
                 this.locationStrategy._beginBackPageNavigation(this.frame);
                 this.locationStrategy.back(null, this.frame);
             }
-        }));
+        });
+        page.on(Page.navigatedFromEvent, navigatedFromCallback);
+        componentRef.onDestroy(() => {
+            if (page) {
+                page.off(Page.navigatedFromEvent, navigatedFromCallback);
+                page = null;
+            }
+        });
 
         const navOptions = this.locationStrategy._beginPageNavigation(this.frame);
 
@@ -374,7 +381,9 @@ export class PageRouterOutlet implements OnDestroy { // tslint:disable-line:dire
         }
 
         this.frame.navigate({
-            create: () => { return page; },
+            create() {
+                return page;
+            },
             clearHistory: navOptions.clearHistory,
             animated: navOptions.animated,
             transition: navOptions.transition