patch 8.0.1794: duplicate term options after renaming

Problem:    Duplicate term options after renaming.
Solution:   Remove the old names 'termkey', 'termsize' and 'terminalscroll'.
diff --git a/src/testdir/screendump.vim b/src/testdir/screendump.vim
index 7065fa0..3c424a0 100644
--- a/src/testdir/screendump.vim
+++ b/src/testdir/screendump.vim
@@ -57,7 +57,7 @@
   " Add -v to have gvim run in the terminal (if possible)
   let cmd .= ' -v ' . a:arguments
   let buf = term_start(cmd, {'curwin': 1, 'term_rows': rows, 'term_cols': cols})
-  if &termsize == ''
+  if &termwinsize == ''
     call assert_equal([rows, cols], term_getsize(buf))
   else
     let rows = term_getsize(buf)[0]