Josh Goldberg cd88f6a319 Added error for class properties used within their own declaration
Fixes #5987.

Usages of a class property in a preceding property already gave an error, but the following doesn't yet:

```ts
class Test {
    x: number = this.x;
}
```

As with other use-before-declare checking, IIFEs are not treated as invalid uses.
2019-01-13 13:30:58 -05:00
..
2018-10-24 13:51:24 -07:00
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