patch 8.2.4508: Vim9: cannot assign to a global variable on the command line

Problem:    Vim9: cannot assign to a global variable on the command line.
Solution:   Allow using :vim9cmd for assignment on the command line.
diff --git a/src/testdir/dumps/Test_vim9_reject_declaration.dump b/src/testdir/dumps/Test_vim9_reject_declaration_1.dump
similarity index 100%
rename from src/testdir/dumps/Test_vim9_reject_declaration.dump
rename to src/testdir/dumps/Test_vim9_reject_declaration_1.dump
diff --git a/src/testdir/dumps/Test_vim9_reject_declaration_2.dump b/src/testdir/dumps/Test_vim9_reject_declaration_2.dump
new file mode 100644
index 0000000..a6d516c
--- /dev/null
+++ b/src/testdir/dumps/Test_vim9_reject_declaration_2.dump
@@ -0,0 +1,6 @@
+> +0&#ffffff0@74
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+|1+0#0000000&|2|3| @53|0|,|0|-|1| @8|A|l@1| 
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 70a3ffb..f60fb36 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -3365,7 +3365,10 @@
 def Run_test_reject_declaration()
   var buf = g:RunVimInTerminal('', {'rows': 6})
   term_sendkeys(buf, ":vim9cmd var x: number\<CR>")
-  g:VerifyScreenDump(buf, 'Test_vim9_reject_declaration', {})
+  g:VerifyScreenDump(buf, 'Test_vim9_reject_declaration_1', {})
+  term_sendkeys(buf, ":\<CR>")
+  term_sendkeys(buf, ":vim9cmd g:foo = 123 | echo g:foo\<CR>")
+  g:VerifyScreenDump(buf, 'Test_vim9_reject_declaration_2', {})
 
   # clean up
   g:StopVimInTerminal(buf)