trackBy-function not reporting failures when `[ngForOf]` is used

**Reproduction:**

```JSON
{
  "rules": {
    "trackBy-function": true
  }
}
```

```html
<ng-template ngFor let-item [ngForOf]="[1, 2, 3]" let-i="index">
  {{ item }}
</ng-template>
```

**Expected behavior:**
Failure. Missing `[ngForTrackBy]`.

**Actual behavior:**
No failure.