[reports] Cannot expand plots

For some reason, this stopped working.

Example:

http://beatweb-staging/search/anjos/for_flavio/

Then click on the button "expand" to expand the plots. Open the JS console to see:

Uncaught TypeError: Cannot read property 'split' of undefined

From: http://beatweb-staging/static/experiments/js/utils.js?v1.0.0b13, line 223