Resolve "Performance bar prevent the auto-scroll-to-bottom when visiting a job's page"

What does this MR do?

The performance bar kicks in after the job code, which means that the cached variables for document and window don't take the performance bar in consideration.

We need to always query at the given moment because of that. Which can degrade performance.

Screen_Recording_2017-12-21_at_03.49_PM

Does this MR meet the acceptance criteria?

• Review
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

Closes #41120 (closed)

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/41120