Data-point mouseover should show correct Ruby when some Rubies are hidden.

[brianhempel]

If you toggle some rubies to be hidden, mousing over a datapoint can show the wrong ruby.

[rakvium]

+1, it's annoying.

To reproduce:

1. Go to main page
2. Move the cursor to hover on result of version of ruby, Nth (not first, for example, second) in the list.
   The data in the pop-up for the second in the list will show you the right results for the Nth version:
   
3. Click on the (N-1)st (for example, first) version in the list.
4. Move the cursor to hover on result of version of ruby, which is Nth in the list again.
   The data in the pop-up for the Nth ruby version in the list will show you the results for (N-1)st: