web: pressing CTRL+SPACE with smart search enabled doesn't show filter list

Created by: ryan-blunden

• Sourcegraph version: sourcegraph.com (62791_2020-05-06_9c3ecdc)
• Platform information: macOS, Chrome 81.0.4044.129

Steps to reproduce:

1. Ensure the experimental smart search field is enabled
2. Put focus into the search field
3. Press CTRL+SPACE
4. Observe that the list of filters does not display.