generic bounds don't work with syntax generics

```py
from typing import TypeVar, Collection

T = TypeVar('T')
L = TypeVar('L', bound=Collection[T])
def foo(l: L) -> T:
return l[0]

reveal_type(foo([1])) # int

def bar[T2, L2: Collection[T2]](l: L2) -> T:
return l[0]

reveal_type(bar([1])) # Never
```

Start by running the two generic examples in the issue and compare their reveal_type results. Trace how traditional TypeVar bounds and syntax generic bounds are handled, then verify that bar([1]) infers int rather than Never and that the existing foo behavior remains unchanged.

Written by the indexing model from the issue text.