refactor(router): clean up RouterLinkActive (#13273)

PR Close #13273

modules/@angular/router/src/directives/router_link_active.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {AfterContentInit, ContentChildren, Directive, ElementRef, Input, OnChanges, OnDestroy, QueryList, Renderer} from '@angular/core';
+import {AfterContentInit, ChangeDetectorRef, ContentChildren, Directive, ElementRef, Input, OnChanges, OnDestroy, QueryList, Renderer} from '@angular/core';
 import {Subscription} from 'rxjs/Subscription';
 
 import {NavigationEnd, Router} from '../router';
@@ -103,22 +103,18 @@ export class RouterLinkActive implements OnChanges,
   get isActive(): boolean { return this.hasActiveLink(); }
 
   ngAfterContentInit(): void {
-    this.links.changes.subscribe(s => this.update());
-    this.linksWithHrefs.changes.subscribe(s => this.update());
+    this.links.changes.subscribe(_ => this.update());
+    this.linksWithHrefs.changes.subscribe(_ => this.update());
     this.update();
   }
 
   @Input()
   set routerLinkActive(data: string[]|string) {
-    if (Array.isArray(data)) {
-      this.classes = <any>data;
-    } else {
-      this.classes = data.split(' ');
-    }
+    this.classes = (Array.isArray(data) ? data : data.split(' ')).filter(c => !!c);
   }
 
-  ngOnChanges(changes: {}): any { this.update(); }
-  ngOnDestroy(): any { this.subscription.unsubscribe(); }
+  ngOnChanges(changes: {}): void { this.update(); }
+  ngOnDestroy(): void { this.subscription.unsubscribe(); }
 
   private update(): void {
     if (!this.links || !this.linksWithHrefs || !this.router.navigated) return;

tools/public_api_guard/router/index.d.ts

@@ -262,10 +262,10 @@ export declare class RouterLinkActive implements OnChanges, OnDestroy, AfterCont
     routerLinkActiveOptions: {
         exact: boolean;
     };
-    constructor(router: Router, element: ElementRef, renderer: Renderer);
+    constructor(router: Router, element: ElementRef, renderer: Renderer, cdr: ChangeDetectorRef);
     ngAfterContentInit(): void;
-    ngOnChanges(changes: {}): any;
-    ngOnDestroy(): any;
+    ngOnChanges(changes: {}): void;
+    ngOnDestroy(): void;
 }
 
 /** @stable */