Deprecate quic_fix_handling_of_bad_prox_packet

gfe-relnote: deprecate gfe2_restart_flag_quic_fix_handling_of_bad_prox_packet
PiperOrigin-RevId: 295810991
Change-Id: Ie8e1bcbdeb6ae13702f263556c952dbb260f03af
diff --git a/quic/core/quic_framer.cc b/quic/core/quic_framer.cc
index 5d9acca..00bd6f4 100644
--- a/quic/core/quic_framer.cc
+++ b/quic/core/quic_framer.cc
@@ -423,8 +423,7 @@
       current_received_frame_type_(0) {
   DCHECK(!supported_versions.empty());
   version_ = supported_versions_[0];
-  DCHECK(version_.IsKnown() ||
-         !GetQuicRestartFlag(quic_fix_handling_of_bad_prox_packet))
+  DCHECK(version_.IsKnown())
       << ParsedQuicVersionVectorToString(supported_versions_);
 }