Function Expression Decorators (Stage 0)

Author: @IgorMinar
Spec doc: https://docs.google.com/document/d/1ikxIP5-RVYq6d_f8lAvf3pKC00W78ueyp-xIZ6q67uU/edit#
Spec Repo: N/A
Related proposals: https://github.com/tc39/proposal-decorators, https://docs.google.com/document/d/1Qpkqf_8NzAwfD8LdnqPjXAQ2wwh8BBUGynhn-ZlCWT0/edit

### Example

```javascript
scheduleForFrequentReexecution(@memoize function(value) {
value++
});
```

Start with the linked Google specification, the TC39 decorators proposal, and the related proposal document. The issue names no repository files, tests, or implementation entry point, and it does not define a concrete completion criterion beyond exploring the Stage 0 proposal.

Written by the indexing model from the issue text.