patch 8.2.1029: Vim9: cannot chain function calls with -> at line start

Problem:    Vim9: cannot chain function calls with -> at line start.
Solution:   Peek ahead for a following line starting with "->". (closes #6306)
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index f87e920..b46e04b 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -1036,6 +1036,24 @@
   	map('string(v:key)')
   assert_equal(['0', '1', '2'], l)
 
+  l = range
+  	->map('string(v:key)')
+  assert_equal(['0', '1', '2'], l)
+
+  l = range # comment
+  	->map('string(v:key)')
+  assert_equal(['0', '1', '2'], l)
+
+  l = range
+
+  	->map('string(v:key)')
+  assert_equal(['0', '1', '2'], l)
+
+  l = range
+	# comment
+  	->map('string(v:key)')
+  assert_equal(['0', '1', '2'], l)
+
   assert_equal('1', l[
 	1])