`path.evaluate` wrongly retruns with confidence for "block-scoped" var's

## Bug Report

**Current Behavior**
`path.evaluate` is broken for `var` scopes.

**Input Code**
http://astexplorer.net/#/gist/583ea7d0c0501af69a1b224526f7f864

**Expected behavior/code**
Cannot return with confidence that `doesExist` is `true`.

**Babel Configuration (.babelrc, package.json, cli command)**
N/A

**Environment**
N/A