MD file preview is broken when table contains empty rows
### Summary
If original MD file contains table with empty row, the preview is broken (see screenshoots)
### Steps to reproduce
- add table to MD file
- add empty row (on our project we use empty rows to separate group of rows)
### What is the current *bug* behavior?
Preview is broken
### What is the expected *correct* behavior?
Preview shows table with thin empty row
### Relevant logs and/or screenshots
source

preview

GitLab Community Edition 11.5.3
issue