refactor(outlet): introduce isNSEmptyOutlet property

Author: ADjenkov

Diff for: nativescript-angular/router/ns-location-strategy.ts

@@ -25,6 +25,7 @@ export class Outlet {
     path: string;
     pathByOutlets: string;
     states: Array<LocationState> = [];
+    isNSEmptyOutlet: boolean;
 
     // Used in reuse-strategy by its children to determine if they should be detached too.
     shouldDetach: boolean = true;
@@ -41,10 +42,6 @@ export class Outlet {
         return this.frames.indexOf(frame) > -1;
     }
 
-    isNSEmptyOutlet(): boolean {
-        return this.frames.length > 1;
-    }
-
     peekState(): LocationState {
         if (this.states.length > 0) {
             return this.states[this.states.length - 1];

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

@@ -280,6 +280,7 @@ export class PageRouterOutlet implements OnDestroy { // tslint:disable-line:dire
             return;
         }
 
+        this.outlet.isNSEmptyOutlet = this.isEmptyOutlet;
         this.locationStrategy.updateOutletFrame(this.outlet, this.frame);
 
         if (this.outlet && this.outlet.isPageNavigationBack) {

Diff for: nativescript-angular/router/router-extensions.ts

@@ -96,7 +96,7 @@ export class RouterExtensions {
         let relativeRoute = options.relativeTo || rootRoute;
 
         const relativeRouteOutlet = this.findOutletByRoute(relativeRoute);
-        const isNSEmptyOutlet = relativeRouteOutlet && relativeRouteOutlet.isNSEmptyOutlet();
+        const isNSEmptyOutlet = relativeRouteOutlet && relativeRouteOutlet.isNSEmptyOutlet;
 
         // Lazy named outlet has added 'primary' inner NSEmptyOutlet child.
         // Take parent route when `relativeTo` option points to the outer named outlet.
@@ -110,7 +110,7 @@ export class RouterExtensions {
         for (let index = 0; index < routesToMatch.length; index++) {
             const currentRoute = routesToMatch[index];
             if (outlets.some(currentOutlet => currentOutlet === currentRoute.outlet)) {
-                let outlet = this.findOutletByRoute(currentRoute);
+                const outlet = this.findOutletByRoute(currentRoute);
 
                 if (outlet) {
                     outletsToBack.push(outlet);