Incorrect error for parameter properties references

```ts
class Foo {
    constructor(public x = 12, public y = x.toFixed()) {}
}
```

**Expected behavior:**
No error.

**Actual behavior:**
Can't find name 'x' in the expression 'x.toFixed()'.

Caused by https://github.com/Microsoft/TypeScript/pull/26317, so the fix should be an easy modification to that new code.