patch 8.2.2245: Vim9: return value of winrestcmd() cannot be executed

Problem:    Vim9: return value of winrestcmd() cannot be executed.
Solution:   Put colons before each range. (closes #7571)
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index 4abdcdb..3fd3e6d 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -716,5 +716,15 @@
   close
 enddef
 
+def Test_winrestcmd()
+  split
+  var cmd = winrestcmd()
+  wincmd _
+  exe cmd
+  assert_equal(cmd, winrestcmd())
+  close
+enddef
+
+
 
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker