patch 8.1.2190: syntax test fails on Mac

Problem:    Syntax test fails on Mac.
Solution:   Limit the window size to 20 rows.
diff --git a/src/testdir/test_syntax.vim b/src/testdir/test_syntax.vim
index c87b3d6..21ee8dc 100644
--- a/src/testdir/test_syntax.vim
+++ b/src/testdir/test_syntax.vim
@@ -538,9 +538,7 @@
   endif
   call writefile([
 	\ '/* comment line at the top */',
-	\ '  int',
-	\ 'main(int argc, char **argv)// another comment',
-	\ '{',
+	\ 'int main(int argc, char **argv) { // another comment',
 	\ '#if 0',
 	\ '   int   not_used;',
 	\ '#else',
@@ -564,7 +562,7 @@
   " response to t_RB corrects it to "light".
   let $COLORFGBG = '15;0'
 
-  let buf = RunVimInTerminal('Xtest.c', #{rows: 22})
+  let buf = RunVimInTerminal('Xtest.c', {})
   call term_sendkeys(buf, ":syn keyword Search Note\r")
   call term_sendkeys(buf, ":syn match Error /^\\s\\+$/\r")
   call term_sendkeys(buf, ":set hlsearch\r")