Alex Rickabaugh 2c41bb8490 fix(compiler): type-checking error for duplicate variables in templates ()
It's an error to declare a variable twice on a specific template:

```html
<div *ngFor="let i of items; let i = index">
</div>
```

This commit introduces a template type-checking error which helps to detect
and diagnose this problem.

Fixes 

PR Close 
2020-03-03 13:52:50 -08:00
..
2019-02-28 12:06:36 -08:00