patch 8.2.0730: Vim9: Assignment to dict member does not work

Problem:    Vim9: Assignment to dict member does not work.
Solution:   Parse dict assignment. Implement getting dict member.
diff --git a/src/testdir/test_vim9_cmd.vim b/src/testdir/test_vim9_cmd.vim
index 70437b9..12260c3 100644
--- a/src/testdir/test_vim9_cmd.vim
+++ b/src/testdir/test_vim9_cmd.vim
@@ -44,5 +44,27 @@
   delete('Xthemine.vim')
 enddef
 
+def Test_assign_list()
+  let l: list<string> = []
+  l[0] = 'value'
+  assert_equal('value', l[0])
+
+  l[1] = 'asdf'
+  assert_equal('value', l[0])
+  assert_equal('asdf', l[1])
+  assert_equal('asdf', l[-1])
+  assert_equal('value', l[-2])
+enddef
+
+def Test_assign_dict()
+  let d: dict<string> = {}
+  d['key'] = 'value'
+  assert_equal('value', d['key'])
+
+  d[123] = 'qwerty'
+  assert_equal('qwerty', d[123])
+  assert_equal('qwerty', d['123'])
+enddef
+
 
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker