patch 9.0.1453: typos in source code and tests

Problem:    Typos in source code and tests.
Solution:   Fi the typos. (Dominique Pellé, closes #12217)
diff --git a/src/testdir/test_textprop.vim b/src/testdir/test_textprop.vim
index cd141eb..3d196d9 100644
--- a/src/testdir/test_textprop.vim
+++ b/src/testdir/test_textprop.vim
@@ -1570,7 +1570,7 @@
   call prop_add(2, 7, {'length': 2, 'type': 'number'})
   call prop_add(3, 6, {'length': 2, 'type': 'number'})
   call prop_add(4, 7, {'length': 2, 'type': 'number'})
-  " The highlighted "is" in line 1, 2 and 4 is kept and ajudsted.
+  " The highlighted "is" in line 1, 2 and 4 is kept and adjusted.
   " The highlighted "is" in line 3 is deleted.
   let expected = [
         \ #{type_bufnr: 0, id: 0, col: 6, end: 1, type: 'number', length: 2, start: 1},