fix(virtual-scroll): working in angular

packages/angular/src/directives/virtual-utils.ts

@@ -0,0 +1,14 @@
+
+export class VirtualContext {
+
+  constructor(public $implicit: any, public index: number, public count: number) { }
+
+  get first(): boolean { return this.index === 0; }
+
+  get last(): boolean { return this.index === this.count - 1; }
+
+  get even(): boolean { return this.index % 2 === 0; }
+
+  get odd(): boolean { return !this.even; }
+
+}