Fix FPI test for <track> element

In our first-party isolation tests in legacy/trac#13749 (moved).2, I found that the <track> element test seems to be failing. I should try to fix this.

added component::applications/tor browser in Legacy / Trac owner::tbb-team in Legacy / Trac priority::medium in Legacy / Trac resolution::worksforme in Legacy / Trac severity::normal in Legacy / Trac status::closed in Legacy / Trac type::defect in Legacy / Trac labels

Closing this ticket, because the element test does already work in our ESR52 branch.

Trac:
Status: new to closed
Resolution: N/A to worksforme

closed

moved from legacy/trac#21679 (moved)

added Bug label and removed 1 deleted label

removed 1 deleted label