Problem: Insufficient testing for invalid function arguments.
Solution: Add more tests. (Yegappan Lakshmanan, closesvim/vim#5988)
99fa721944
Omit test_listener.vim: changed again in patch 8.2.1183.
Omit test_textprop.vim: changed again in patch 8.2.1183.
Cherry-pick quickfix feature checks from patch 8.1.2373.
Omit Test_saveas() change: duplicate and removed in patch 8.2.0866.