Dashboards with saved searches don't render dark theme correctly on Kibana 6.7.0

[dougburks]

Kibana version:
6.7.0

Elasticsearch version:
6.7.0

Server OS version:
Ubuntu 16.04

Browser version:
Chromium 73

Browser OS version:
Ubuntu 16.04

Original install method (e.g. download page, yum, from source, etc.):
Docker

Describe the bug:
In Kibana 6.5.4, dashboards with saved searches with dark theme render properly.

In Kibana 6.7.0, dashboards with saved searches with dark theme do not render properly. The expanded detail displays in light theme rather than dark theme.

Steps to reproduce:

1. Create a saved search.
2. Create a dashboard with dark theme enabled and add the saved search.
3. Expand one of the documents in the saved search and notice that the detail shows in light theme instead of dark theme.

Expected behavior:
Saved search detail should respect dark theme as it did in previous versions of Kibana.

Screenshots (if relevant):
Here's a screenshot of the proper behavior in Kibana 6.5.4:

Here's a screenshot of the improper behavior in Kibana 6.7.0:

Errors in browser console (if relevant):

Provide logs and/or server output (if relevant):

Any additional context:

[elasticmachine]

Pinging @elastic/kibana-app

[timroes]

@cchaos do you remember if that was touched by any of the SASS refactorings?

[cchaos]

Well, everything was touched during the SASS refactors. 😉

In this particular case it looks like a background color was added to the single doc view, not realizing the view also occurred in dark dashboards.

I can push a quick fix PR, but not sure what the status is for PR's against 6.7.

[timroes]

@cchaos I think since this is a regression from an earlier version and 6.7 will be maintained for over a year, we should release a fix for that in a patch version. If you can put up a PR, I'll highly appreciate that. Thanks a lot!