var declaration in eval should conflict with outer block-scoped let declaration

The following should be an error and it is an error in v8 and sm

```js
if (true) {
let fo5_l = 123;

if (true) {
// conflict with `let` declaration in outer block scope - should fail.
try { eval("var fo5_l = 456") } catch (e) { print(e); }
}
}
```

We do handle this correctly when outer `let` is at the top scope, but not if it is in an intermediate block scope.

Reproduce the issue by running the provided JavaScript snippet and observe whether eval("var fo5_l = 456") conflicts with the outer block-scoped let. Trace the eval handling and block-scope conflict checks, then verify that the intermediate-block case throws an error while the existing top-scope behavior remains correct.

Written by the indexing model from the issue text.