Fix QpackDecoder::EncoderStreamRelativeIndexToAbsoluteIndex(), simplify QpackProgressiveDecoder::RequestStreamRelativeIndexToAbsoluteIndex().

gfe-relnote: n/a, change to QUIC v99-only code.  Protected by existing disabled gfe2_reloadable_flag_quic_enable_version_99.
PiperOrigin-RevId: 263413585
Change-Id: I1aab74f6f0d825079779f4d402c9ae1c94a368cd
diff --git a/quic/core/qpack/qpack_decoder_test.cc b/quic/core/qpack/qpack_decoder_test.cc
index 506d60c..556053b 100644
--- a/quic/core/qpack/qpack_decoder_test.cc
+++ b/quic/core/qpack/qpack_decoder_test.cc
@@ -425,7 +425,7 @@
 
 TEST_P(QpackDecoderTest, EncoderStreamErrorInvalidDynamicTableEntry) {
   EXPECT_CALL(encoder_stream_error_delegate_,
-              OnEncoderStreamError(Eq("Dynamic table entry not found.")));
+              OnEncoderStreamError(Eq("Invalid relative index.")));
 
   DecodeEncoderStreamData(QuicTextUtils::HexDecode(
       "6294e703626172"  // Add literal entry with name "foo" and value "bar".
@@ -436,7 +436,7 @@
 
 TEST_P(QpackDecoderTest, EncoderStreamErrorDuplicateInvalidEntry) {
   EXPECT_CALL(encoder_stream_error_delegate_,
-              OnEncoderStreamError(Eq("Dynamic table entry not found.")));
+              OnEncoderStreamError(Eq("Invalid relative index.")));
 
   DecodeEncoderStreamData(QuicTextUtils::HexDecode(
       "6294e703626172"  // Add literal entry with name "foo" and value "bar".