(fix) missing $implicit keyword in zone component

[hebus]

Without this keyword, let-data is undefined here:

<!-- data is an array -->
<ng-template #array let-data>
  <ng-container *ngFor="let d of data; let index = index; let first = first"
    [ngTemplateOutlet]="zone"
    [ngTemplateOutletContext]="{ index, first }">
  </ng-container>
</ng-template>