Fix generated JavaScript in profiles

[ruricolist]

This fixes several bugs in the JavaScript generate for HTML profiles:

• Charts would not be shown at all if code were not available.
• "Graph iterations of selected" did not work on relations because the relevant code was using the wrong index.
• The "Go back" button did not work (calling a goBack function deleted in c6d2b2d).

[codecov]

Codecov Report

Merging #2388 (0334b07) into master (5b42c1e) will increase coverage by 0.01%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2388      +/-   ##
==========================================
+ Coverage   77.54%   77.56%   +0.01%     
==========================================
  Files         467      467              
  Lines       30785    30785              
==========================================
+ Hits        23871    23877       +6     
+ Misses       6914     6908       -6     

Impacted Files	Coverage Δ
src/include/souffle/utility/ParallelUtil.h	84.49% <0.00%> (-0.78%)	⬇️
src/include/souffle/datastructure/BTree.h	98.33% <0.00%> (+0.41%)	⬆️
src/include/souffle/profile/ProfileEvent.h	98.00% <0.00%> (+5.00%)	⬆️

[quentin]

Thanks for the fix.
I guess we have no way to automate tests on the profile pages.