Remove some TLSv1.3 TODOs that are no longer relevant

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2737)

ssl/ssl_lib.c

@@ -1603,11 +1603,6 @@ int SSL_read_early(SSL *s, void *buf, size_t num, size_t *readbytes)
         return SSL_READ_EARLY_ERROR;
     }
 
-    /*
-     * TODO(TLS1.3): Somehow we need to check that we're not receiving too much
-     * data
-     */
-
     switch (s->early_data_state) {
     case SSL_EARLY_DATA_NONE:
         if (!SSL_in_before(s)) {
@@ -1804,11 +1799,6 @@ int SSL_write_early(SSL *s, const void *buf, size_t num, size_t *written)
         return 0;
     }
 
-    /*
-     * TODO(TLS1.3): Somehow we need to check that we're not sending too much
-     * data
-     */
-
     switch (s->early_data_state) {
     case SSL_EARLY_DATA_NONE:
         if (!SSL_in_before(s)) {

ssl/statem/statem_clnt.c

@@ -123,11 +123,6 @@ static int ossl_statem_client13_read_transition(SSL *s, int mt)
 {
     OSSL_STATEM *st = &s->statem;
 
-    /*
-     * TODO(TLS1.3): This is still based on the TLSv1.2 state machine. Over time
-     * we will update this to look more like real TLSv1.3
-     */
-
     /*
      * Note: There is no case for TLS_ST_CW_CLNT_HELLO, because we haven't
      * yet negotiated TLSv1.3 at that point so that is handled by

ssl/t1_enc.c

@@ -483,13 +483,7 @@ size_t tls1_final_finish_mac(SSL *s, const char *str, size_t slen,
 int tls1_generate_master_secret(SSL *s, unsigned char *out, unsigned char *p,
                                 size_t len, size_t *secret_size)
 {
-    /*
-     * TODO(TLS1.3): We haven't implemented TLS1.3 key derivation yet. For now
-     * we will just force no use of EMS (which adds complications around the
-     * handshake hash). This will need to be removed later
-     */
-    if ((s->session->flags & SSL_SESS_FLAG_EXTMS)
-            && !SSL_IS_TLS13(s)) {
+    if (s->session->flags & SSL_SESS_FLAG_EXTMS) {
         unsigned char hash[EVP_MAX_MD_SIZE * 2];
         size_t hashlen;
         /*