Bug 1520062 - Remove expected WPT leak threshold for /css/css-fonts/font-display/ r=kershaw

Differential Revision: https://phabricator.services.mozilla.com/D16550

--HG--
extra : moz-landing-system : lando

testing/web-platform/meta/css/css-fonts/font-display/__dir__.ini

@@ -1,2 +1 @@
 lsan-allowed: [Alloc, AllocateProtoAndIfaceCache, EntrySlotOrCreate, Realloc, alloc_system::platform::_$LT$impl$u20$core..alloc..GlobalAlloc$u20$for$u20$alloc_system..System$GT$::alloc, alloc_system::platform::_$LT$impl$u20$core..alloc..GlobalAlloc$u20$for$u20$alloc_system..System$GT$::realloc, mozilla::dom::ChromeUtils::GenerateQI, mozilla::dom::Performance::CreateForMainThread, mozilla::dom::PerformanceMainThread::CreateNavigationTimingEntry, mozilla::net::nsStandardURL::TemplatedMutator]
-leak-threshold: [tab:358400]