Problem:    Some Normal mode commands not fully tested.
Solution:   Add a few more tests. (Yegappan Lakshmanan, closes vim/vim#7073)
https://github.com/vim/vim/commit/d1ad99b65470d3e754f6a0588a6b0dc2214a1eab

Cherry-pick test_registers.vim change from patch 8.2.0644.

Problem:    Reading past end of line with "gf" in Visual block mode.
Solution:   Do not include the NUL in the length.
https://github.com/vim/vim/commit/395bd1f6d3edc9f7edb5d1f2d7deaf5a9e3ab93c

Omit trailing space: removed in patch 9.0.0126.

vim-patch:9.0.0126: expanding file names fails in dir with more than 255 entries

Problem:    Expanding file names fails in directory with more than 255
            entries.
Solution:   Use an int instead of char_u to count. (John Drouhard,
            closes vim/vim#10818)
https://github.com/vim/vim/commit/95fca12b0e8a351ce4416417323db24c63eb940a

Problem:    Not enough testing for movement commands.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#6313)
https://github.com/vim/vim/commit/bdd2c290d3cda69e0046c42f0c651f60bc510a16

Cherry-pick test_functions.vim changes from patch 8.2.0183.
Cherry-pick Test_normal18_z_fold() change from patch 8.2.0540.

Problem:    Insufficient testing for src/window.c.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#6345)
https://github.com/vim/vim/commit/5d3c9f8c2a0fc29ba4ac8e0f052378b64d9e3dd3

Cherry-pick test_tagjump.vim changes from patch 8.1.2373.

This can avoid divergences from Vim in some small places.

Problem:    Get ml_get error when deleting a line in 'completefunc'. (Yegappan
            Lakshmanan)
Solution:   Lock the text while evaluating 'completefunc'.
https://github.com/vim/vim/commit/ff06f283e3e4b3ec43012dd3b83f8454c98f6639

Fix a mistake in the porting of patch 8.1.0098.
Cherry-pick Test_run_excmd_with_text_locked() from patch 8.2.0270.
Cherry-pick test_gf.vim changes from patch 8.2.0369.
Cherry-pick message change from later patches.

Problem:    The EBCDIC support is outdated.
Solution:   Remove the EBCDIC support.
https://github.com/vim/vim/commit/424bcae1fb0f69e0aef5e0cf84fd771cf34a0fb7

Also remove a comment in buf_init_chartab() as it is for enc_dbcs only.

Skip test_expr.vim: the check was already removed when patch 7.4.2265
was first ported.

Problem:    "gF" does not use line number after file in Visual mode.
Solution:   Look for ":123" after the Visual area. (closes vim/vim#6952)
https://github.com/vim/vim/commit/efd5d8a967ba80f9e2826c35be98344d8f00af77

Cherry-pick test_gf_visual changes from patch 8.2.1040.