Change HTTP/3 frames from Lengh-Type-Value to Type-Length-Value.

Updating to IETF draft 19.

gfe-relnote: n/a --version 99 only, not yet enabled.
PiperOrigin-RevId: 244687780
Change-Id: Id8f42caad0c1dd2978e1a0a45aa2f462dcd0bcf8
diff --git a/quic/core/http/http_encoder.cc b/quic/core/http/http_encoder.cc
index df04be2..9de1571 100644
--- a/quic/core/http/http_encoder.cc
+++ b/quic/core/http/http_encoder.cc
@@ -255,8 +255,8 @@
 bool HttpEncoder::WriteFrameHeader(QuicByteCount length,
                                    HttpFrameType type,
                                    QuicDataWriter* writer) {
-  return writer->WriteVarInt62(length) &&
-         writer->WriteVarInt62(static_cast<uint64_t>(type));
+  return writer->WriteVarInt62(static_cast<uint64_t>(type)) &&
+         writer->WriteVarInt62(length);
 }
 
 QuicByteCount HttpEncoder::GetTotalLength(QuicByteCount payload_length,