transport-cc: remove unnecessary if block

which can no longer happen since the end index and delta sizes are
checked in the surrounding condition.
Replace with a DCHECK to guard against potential errors.

BUG=None

Change-Id: I868d54c5923de773f248d10a40dbc6b2c563b0f1
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/231957
Reviewed-by: Johannes Kron <kron@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@nvidia.com>
Cr-Commit-Position: refs/heads/main@{#35210}
diff --git a/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc b/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc
index 16f88a0..71d0ab5 100644
--- a/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc
+++ b/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc
@@ -454,11 +454,7 @@
   // Determine if timestamps, that is, recv_delta are included in the packet.
   if (end_index >= index + recv_delta_size) {
     for (size_t delta_size : delta_sizes) {
-      if (index + delta_size > end_index) {
-        RTC_LOG(LS_WARNING) << "Buffer overflow while parsing packet.";
-        Clear();
-        return false;
-      }
+      RTC_DCHECK_LE(index + delta_size, end_index);
       switch (delta_size) {
         case 0:
           if (include_lost_)