[level map] cleanup and remove assertions

Removed assertions were not properly set up and may cause decoding failure when USE_CASUAL_CTX is enabled. This CL does not change bitstream.

Change-Id: Ib9193cbda32f342335a79aca39e9cc49204a0ec9

av1/decoder/decodetxb.c

diff --git a/av1/decoder/decodetxb.c b/av1/decoder/decodetxb.c
index 30330f0..aa5cda7 100644
--- a/av1/decoder/decodetxb.c
+++ b/av1/decoder/decodetxb.c
@@ -160,7 +160,6 @@
     c = *eob - 1 - i;
     int is_nz;
     int coeff_ctx = get_nz_map_ctx(levels, c, scan, bwl, height, tx_type, 1);
-    // int eob_ctx = get_eob_ctx(tcoeffs, scan[c], txs_ctx, tx_type);
 
     if (c < *eob - 1) {
       is_nz = av1_read_record_bin(
@@ -180,16 +179,12 @@
       int k;
       for (k = 0; k < NUM_BASE_LEVELS; ++k) {
         int ctx = coeff_ctx;
-#if 0  // USE_CAUSAL_BASE_CTX read_coeffs
-        int is_k = av1_read_record_bit(counts, r, ACCT_STR);
-#else
         int is_k = av1_read_record_bin(
             counts, r, ec_ctx->coeff_base_cdf[txs_ctx][plane_type][k][ctx], 2,
             ACCT_STR);
         if (counts) ++counts->coeff_base[txs_ctx][plane_type][k][ctx][is_k];
 
-#endif
-        // is_k = 1 if level > (k+1)
+        // semantic: is_k = 1 if level > (k+1)
         if (is_k == 0) {
           cul_level += k + 1;
           break;

av1/encoder/encodetxb.c

diff --git a/av1/encoder/encodetxb.c b/av1/encoder/encodetxb.c
index e715a54..dbb7d90 100644
--- a/av1/encoder/encodetxb.c
+++ b/av1/encoder/encodetxb.c
@@ -318,7 +318,6 @@
   for (int i = 0; i < eob; ++i) {
     c = eob - 1 - i;
     coeff_ctx = get_nz_map_ctx(tcoeff, c, scan, bwl, height, tx_type, 0);
-    if (c == eob - 1) assert(coeff_ctx == 0);
 
     tran_low_t v = tcoeff[scan[c]];
     int is_nz = (v != 0);
@@ -587,7 +586,6 @@
     int level = abs(v);
 #if USE_CAUSAL_BASE_CTX
     coeff_ctx = get_nz_map_ctx(qcoeff, c, scan, bwl, height, tx_type, 0);
-    if (c == eob - 1) assert(coeff_ctx == 0);
 #endif
 
     if (c < eob - 1) {
@@ -2018,7 +2016,6 @@
 
 #if USE_CAUSAL_BASE_CTX
     coeff_ctx = get_nz_map_ctx(tcoeff, c, scan, bwl, height, tx_type, 0);
-    if (c == eob - 1) assert(coeff_ctx == 0);
     if (c < eob - 1) {
       ++(*nz_map_count)[coeff_ctx][is_nz];
       update_cdf(ec_ctx->nz_map_cdf[txsize_ctx][plane_type][coeff_ctx], is_nz,