Bug 1885529 - Make sure HostRecordQueue::mPendingCount is accurate r=necko-reviewers,jesup

When calling MoveToAnotherPendig the record gets removed from the
pending queue, and InsertRecord is called. As InsertRecord again
increments mPendingCount, we need to decrement it when removing from
a pending queue to ensure it's accurate.

Depends on D206498

Differential Revision: https://phabricator.services.mozilla.com/D206503

netwerk/dns/HostRecordQueue.cpp

@@ -166,6 +166,10 @@ void HostRecordQueue::MoveToAnotherPendingQ(nsHostRecord* aRec,
   }
 
   aRec->remove();
+  // We just removed from pending queue. Insert record will
+  // increment this value again.
+  mPendingCount--;
+
   InsertRecord(aRec, aFlags, aProofOfLock);
 }