Make sure HTML editor is visible when adding description. Fixes #2163

[UX] Make sure that HTML editor is visible when adding meta tag
description text from *Add description* menu action.
Avoids situation that "Add description" seems to have no visible
results for novice users.

```bash
npm test
[...]
    ✓ should protect do loops 

  labels
    ✓ should handle continue statements and gotos 
    ✓ should handle labels with comments 
    ✓ should handle things that *look* like labels 


  22 passing (8s)
```