Links to plugins aren't accessible

[William Ashton]

All of the theme/plugin links on /themes, /themes?newest, /plugins, and /plugins?newest had surprising behavior:

• ctrl-click-ing them did not open a new tab, instead navigating in the current tab (this can be a jarring experience when I'm attempting to pick three or four links out of a list and the first one takes the list away from me.)
• Right-clicking on them gives you a standard page menu instead of a link menu with options like "Copy link address" or "Open in new tab"
• None of the links showed up in the tab sequence, so I couldn't tab through the list of plugins.

Tested in both Chrome 75 and Firefox 67 on Fedora Linux.