patch 8.2.0149: maintaining a Vim9 branch separately is more work

Problem:    Maintaining a Vim9 branch separately is more work.
Solution:   Merge the Vim9 script changes.
diff --git a/src/proto/eval.pro b/src/proto/eval.pro
index b086079..14b5f26 100644
--- a/src/proto/eval.pro
+++ b/src/proto/eval.pro
@@ -27,7 +27,12 @@
 int pattern_match(char_u *pat, char_u *text, int ic);
 int eval0(char_u *arg, typval_T *rettv, char_u **nextcmd, int evaluate);
 int eval1(char_u **arg, typval_T *rettv, int evaluate);
+void eval_addblob(typval_T *tv1, typval_T *tv2);
+int eval_addlist(typval_T *tv1, typval_T *tv2);
 int get_option_tv(char_u **arg, typval_T *rettv, int evaluate);
+int get_number_tv(char_u **arg, typval_T *rettv, int evaluate, int want_string);
+int get_string_tv(char_u **arg, typval_T *rettv, int evaluate);
+int get_lit_string_tv(char_u **arg, typval_T *rettv, int evaluate);
 char_u *partial_name(partial_T *pt);
 void partial_unref(partial_T *pt);
 int tv_equal(typval_T *tv1, typval_T *tv2, int ic, int recursive);
@@ -43,6 +48,7 @@
 char_u *tv2string(typval_T *tv, char_u **tofree, char_u *numbuf, int copyID);
 char_u *string_quote(char_u *str, int function);
 int string2float(char_u *text, float_T *value);
+int get_env_tv(char_u **arg, typval_T *rettv, int evaluate);
 pos_T *var2fpos(typval_T *varp, int dollar_lnum, int *fnum);
 int list2fpos(typval_T *arg, pos_T *posp, int *fnump, colnr_T *curswantp);
 int get_env_len(char_u **arg);
@@ -66,6 +72,7 @@
 char_u *tv_get_string_buf_chk(typval_T *varp, char_u *buf);
 void copy_tv(typval_T *from, typval_T *to);
 int item_copy(typval_T *from, typval_T *to, int deep, int copyID);
+void echo_one(typval_T *rettv, int with_space, int *atstart, int *needclr);
 void ex_echo(exarg_T *eap);
 void ex_echohl(exarg_T *eap);
 int get_echo_attr(void);