Missing excess property error with spread

**TypeScript Version:**  3.1.0-dev.201xxxxx

**Code**

```ts
function f(o: { a: number, b: number }): { a: number } {
    return { b: 0, ...o };
}
```

**Expected behavior:**

Error on `b`.

**Actual behavior:**

No error.

Broken by #26798.


**Related Issues:** #27166, #23340
