Previously, getWidenedTypedFromJSPropertyAssignment was not called for
Typescript code. Since property assignments on functions, it is. That
meant that property assignments would incorrectly create a JS container
for empty object literals in a property assignment, even in Typescript:
```ts
const one = () => 1
one.p = {}
one.p.q = {} // should not work in Typescript!
```
Now empty object literals never create expando objects in Typescript,
because getJSExpandoObjectType requires the declaration to be in a JS
file.
