Object.assign({}) seems to always return a type any

<!-- Please try to reproduce the issue with `typescript@next`. It may have already been fixed. --> **TypeScript Version:** 3.3.0-dev.20190110 <!-- Search terms you tried before logging this (so others can find this issue more easily) --> **Search Terms:** Object.assign **Code** ```ts function foo(): {foo: string} { return Object.assign({}); } ``` Interestingly the code: ```ts function bar(): {bar: string} { return Object.assign({}, {bar: 1}); } ``` does report the expected error **Expected behavior:** TypeScript should report an error because the type returned by `return Object.assign({});` does not mach `{foo: string}` but instead the type any is assumed. **Actual behavior:** No error is shown **Playground Link:** https://www.typescriptlang.org/play/index.html#src=function%20foo()%3A%20%7Bfoo%3A%20string%7D%20%7B%0D%0A%20%20%20%20return%20Object.assign(%7B%7D)%3B%0D%0A%7D%0D%0A **Related Issues:** no