Feedback response navigation elements not displayed correctly in Boost

As noticed by markn, the Feedback module page "Show responses" has broken links for navigating through responses. This seems to be a indirect regression of MDL-59313 that started to display links to navigate through activities.

Steps to reproduce:

1. Have a 3.4 site with the Boost theme
2. Have at least 3 activity modules in a course with a Feedback module in the middle (with at least one module before, one after it).
3. Define a simple question in the Feedback
4. Submit answers to the Feedback as at least 3 students (so there are at least 3 responses)
5. As a teacher, go to the "Show responses" tab
6. Click on one of the responses

Expected behaviour:

• Links to navigate through the responses are nicely displayed

Actual behaviour:

• Links to navigate through the responses are broken, the "Back" link is completely covered with the "Jump..." selector.