[Bug] Using `filter` in `itertools.chain` makes them both infer wrong types.

Repro:

import itertools
from typing import List

x: List[int] = [1, 2, 3]
y: List[str] = ["  ", "", "abc"]


it = itertools.chain(x, filter(lambda s: s.strip() == "", y))
reveal_type(it)

Actual output:

main.py:8: error: "object" has no attribute "strip"
main.py:9: note: Revealed type is 'itertools.chain[builtins.object*]'

Expected output:
I was expecting no errors and didn't expect filter to be affected by what it is put in, i.e. if you put filter call separate from itertools.chain, it prevents the first errors about missing strip attr:

f = filter(lambda s: s.strip() == "", y)
it = itertools.chain(x, f)
reveal_type(it)

The revealed type is still wrong though.

Python version: 3.7.6
Mypy version: 0.760 (still occurs on master)
Used flags: --strict

Inizia riproducendo l’esempio fornito con mypy 0.760 o con il master corrente usando --strict, confrontando le forme di filtro inline e separata. Il payload non indica file sorgente né test; il lavoro è completato quando la forma inline non segnala alcun attributo strip mancante e rivela un tipo appropriato per l’elemento della catena invece di object.