Expanding a diff with the context button ("...") omits the first line of context.

Summary

When expanding hidden text in a diff with the context '...' button, the first line of the expanded text is not shown.
Possibly related: https://gitlab.com/gitlab-org/gitlab-ee/issues/7295

Steps to reproduce

1. Open a merge request to view the diff
2. Click on the '...' link at the bottom of the one of the file views
3. The first line of the expanded text is missing. In the image below, there should be text on line 85 of the original file and line 91 of the modified file saying def someFunction():

What is the current bug behavior?

The first line of text is missing.

What is the expected correct behavior?

The first line of text should be present.

Relevant logs and/or screenshots

GitLab Enterprise Edition 11.1.4-ee d17962f9