Revert of relnote: Protect against a QUIC crash bug but logging a DFATAL and

net/quic/quic_packet_generator.cc

Index: net/quic/quic_packet_generator.cc
diff --git a/net/quic/quic_packet_generator.cc b/net/quic/quic_packet_generator.cc
index cc3a79331a1af98a0be4c85ed3b00aeb69398846..49cdc7f6cad43c427b7a70d60e65a2c6653a5e96 100644
--- a/net/quic/quic_packet_generator.cc
+++ b/net/quic/quic_packet_generator.cc
@@ -457,12 +457,7 @@
   char buffer[kMaxPacketSize];
   SerializedPacket serialized_packet =
       packet_creator_.SerializePacket(buffer, kMaxPacketSize);
-  if (serialized_packet.packet == nullptr) {
-    LOG(DFATAL) << "Failed to SerializePacket. fec_policy:" << fec_send_policy_
-                << " should_fec_protect_:" << should_fec_protect_;
-    delegate_->CloseConnection(QUIC_FAILED_TO_SERIALIZE_PACKET, false);
-    return;
-  }
+  DCHECK(serialized_packet.packet);
 
   // There may be AckNotifiers interested in this packet.
   serialized_packet.notifiers.swap(ack_notifiers_);