Signal use_reference_buffer for intra_only frames

BUG=aomedia:851

Change-Id: Ib188f4b640a58c47147cda977a589e527f765a54

av1/decoder/decodeframe.c

diff --git a/av1/decoder/decodeframe.c b/av1/decoder/decodeframe.c
index 9e839b3..434cb0c 100644
--- a/av1/decoder/decodeframe.c
+++ b/av1/decoder/decodeframe.c
@@ -4715,7 +4715,7 @@
 #endif
   cm->error_resilient_mode = aom_rb_read_bit(rb);
 #if CONFIG_REFERENCE_BUFFER
-  if (cm->frame_type == KEY_FRAME) {
+  if (frame_is_intra_only(cm)) {
     cm->use_reference_buffer = aom_rb_read_bit(rb);
 #if !CONFIG_OBU
     read_sequence_header(&pbi->seq_params);

av1/encoder/bitstream.c

diff --git a/av1/encoder/bitstream.c b/av1/encoder/bitstream.c
index 7309386..329f670 100644
--- a/av1/encoder/bitstream.c
+++ b/av1/encoder/bitstream.c
@@ -4578,7 +4578,7 @@
     if (!cm->show_frame) aom_wb_write_bit(wb, cm->intra_only);
   aom_wb_write_bit(wb, cm->error_resilient_mode);
 
-  if (cm->frame_type == KEY_FRAME) {
+  if (frame_is_intra_only(cm)) {
 #if CONFIG_REFERENCE_BUFFER
     aom_wb_write_bit(wb, cm->use_reference_buffer);
     if (cm->use_reference_buffer) {