patch 8.1.0369: continuation lines cannot contain comments

Problem:    Continuation lines cannot contain comments.
Solution:   Support using "\ .
diff --git a/src/testdir/test_eval_stuff.vim b/src/testdir/test_eval_stuff.vim
index 41ba137..bcf45cc 100644
--- a/src/testdir/test_eval_stuff.vim
+++ b/src/testdir/test_eval_stuff.vim
@@ -42,3 +42,14 @@
   call delete('Xfile')
   call delete('Xmkdir', 'rf')
 endfunc
+
+func Test_line_continuation()
+  let array = [5,
+	"\ ignore this
+	\ 6,
+	"\ more to ignore
+	"\ more moreto ignore
+	\ ]
+	"\ and some more
+  call assert_equal([5, 6], array)
+endfunc