fixing overrides last edit mark

## Information

**VIM version**

VIM - Vi IMproved 8.1 (2018 May 18, compiled Feb 18 2019 23:51:40)
macOS version

Operating System: macOS High Sierra 10.13.6

## What went wrong

rustftm fixer (enabled on save) overrides my last edit mark `'.`.

## Reproducing the bug

1. I did this.
Edit some lines in rust source code. Save. File formatted. Go to last edit mark `'.`.
2. Then this happened.
Cursor moves to the end of file instead of last edited line.

### :ALEInfo

Current Filetype: rust
Available Linters: ['cargo', 'rls', 'rustc']
Enabled Linters: ['cargo']
Suggested Fixers:
'remove_trailing_lines' - Remove all blank lines at the end of a file.
'rustfmt' - Fix Rust files with Rustfmt.
'trim_whitespace' - Remove all trailing whitespace characters at the end of every line.
Linter Variables:

let g:ale_rust_cargo_avoid_whole_workspace = 1
let g:ale_rust_cargo_check_all_targets = 0
let g:ale_rust_cargo_check_examples = 0
let g:ale_rust_cargo_check_tests = 1
let g:ale_rust_cargo_clippy_options = '--tests'
let g:ale_rust_cargo_default_feature_behavior = 'default'
let g:ale_rust_cargo_include_features = ''
let g:ale_rust_cargo_use_check = 0
let g:ale_rust_cargo_use_clippy = 1
Global Variables:

let g:ale_cache_executable_check_failures = v:null
let g:ale_change_sign_column_color = 0
let g:ale_command_wrapper = ''
let g:ale_completion_delay = v:null
let g:ale_completion_enabled = 0
let g:ale_completion_max_suggestions = v:null
let g:ale_echo_cursor = 1
let g:ale_echo_msg_error_str = 'Error'
let g:ale_echo_msg_format = '%code: %%s'
let g:ale_echo_msg_info_str = 'Info'
let g:ale_echo_msg_warning_str = 'Warning'
let g:ale_enabled = 1
let g:ale_fix_on_save = 1
let g:ale_fixers = {'rust': ['rustfmt']}
let g:ale_history_enabled = 1
let g:ale_history_log_output = 1
let g:ale_keep_list_window_open = 0
let g:ale_lint_delay = 200
let g:ale_lint_on_enter = 1
let g:ale_lint_on_filetype_changed = 1
let g:ale_lint_on_insert_leave = 0
let g:ale_lint_on_save = 1
let g:ale_lint_on_text_changed = 'normal'
let g:ale_linter_aliases = {}
let g:ale_linters = {}
let g:ale_linters_explicit = 0
let g:ale_list_vertical = 0
let g:ale_list_window_size = 10
let g:ale_loclist_msg_format = '%code: %%s'
let g:ale_lsp_root = {}
let g:ale_max_buffer_history_size = 20
let g:ale_max_signs = -1
let g:ale_maximum_file_size = v:null
let g:ale_open_list = 0
let g:ale_pattern_options = v:null
let g:ale_pattern_options_enabled = v:null
let g:ale_set_balloons = 1
let g:ale_set_highlights = 1
let g:ale_set_loclist = 1
let g:ale_set_quickfix = 0
let g:ale_set_signs = 1
let g:ale_sign_column_always = 0
let g:ale_sign_error = '>>'
let g:ale_sign_info = '--'
let g:ale_sign_offset = 1000000
let g:ale_sign_style_error = '>>'
let g:ale_sign_style_warning = '--'
let g:ale_sign_warning = '--'
let g:ale_statusline_format = v:null
let g:ale_type_map = {}
let g:ale_use_global_executables = v:null
let g:ale_virtualtext_cursor = 0
let g:ale_warn_about_trailing_blank_lines = 1
let g:ale_warn_about_trailing_whitespace = 1

Start by reproducing the issue in Vim 8.1 on macOS with ALE fix-on-save enabled and the Rust rustfmt fixer selected. Compare the last edit mark before and after saving a formatted Rust file; done means the mark still points to the last edited line rather than the end of the file.

Written by the indexing model from the issue text.