This is a port of these two patches combined:
vim-patch:8.1.1524: tests are silently skipped
Problem: Tests are silently skipped.
Solution: Throw an exception for skipped tests in more places.
b0f94c1ff3
vim-patch:8.1.1544: some balloon tests don't run when they can
Problem: Some balloon tests don't run when they can.
Solution: Split GUI balloon tests off into a separate file. (Ozaki Kiichi,
closesvim/vim#4538) Change the feature check into a command for
consistency.
b46fecd345
Omit test_lua.vim: previous patches are N/A
Omit test_memory_usage.vim: previous patches are N/A
Omit test_textprop.vim: previous patches are N/A
Omit test_winbar.vim: previous patches are N/A
Omit test_termcodes.vim: mostly N/A
Skip Test_mouse_positon() because it uses test_setmouse().
Cannot throw error in a Test_nocatch_ test.
Use latest `CheckFeature clipboard_working` for test_quotestar.vim
Cannot be fully ported as the remote_*() functions from +clientserver
are not yet ported. Include the test changes anyway.
line()'s optional winid argument was already ported. (Wasn't added in
this patch; this just adds documentation)
