Bug 1129226 - Update LSan suppression for fixPlainObjectGroup. rs=ryanvm

CLOSED TREE

build/sanitizers/lsan_suppressions.txt

@@ -46,7 +46,7 @@ leak:mozilla::TransportLayerDtls::Setup
 ###
 
 # Bug 981195 - Small leak in the parser. m4
-leak:TypeCompartment::fixObjectGroup
+leak:ObjectGroup::fixPlainObjectGroup
 
 # Bug 982111 - WebM is leaking. m1
 leak:nestegg_read_packet