Log Message:
Update to version 4.9.2

CHanges:

XSS fixed in the Flash fallback files in MediaElement 4.x.

Bundled Theme
#42820 - Twenty Seventeen -watch that language

Customize
#42492 - Selecting menu location changes line height
#42871 - Features box textstrings in Feature Filter area need new linebreak

Database
#42812 - Use MySQLi when available by default

Editor
#42664 - Editor link autocomplete suggestions: no fallback title displayed for \ 
posts with no title
#43012 - Cannot Update Post in Firefox Due to Editor and TinyMCE JavaScript \ 
TypeErrors

External Libraries
#42439 - Update random_compat external library for PHP 7 linting failure

Formatting
#42578 - PHP functions inside <p> tags creates new <p> tag, breaking \ 
the parent tag into two.

Media
#42225 - Whitelist Flac Files
#42447 - Mark test_remove_orientation_data_on_rotate as skipped when \ 
exif_read_data isn't available
#42480 - Consistent suppression of `getimagesize()` errors
#42720 - Remove unnecessary MediaElement.js files

Plugins
#43082 - Add plugins search results: the plugin details modal opens in the \ 
thickbox modal

REST API
#42828 - Hard-coded 403 status in REST response should use \ 
`rest_authorization_required_code()`

Taxonomy
#42771 - WP_Term::get_instance() regression for non-category terms queried with \ 
'category' taxonomy
#42605 - category_description() does not work properly since 4.9
#42717 - get_category_link() accepting object but not id

TinyMCE
#42416 - Code assumes iframe mode, exception in inline mode

Upgrade/Install
#42963 - Improve deletion of $_old_files during upgrades

Widgets
#42603 - Widgets Warning after activating theme and on dashboard widgets page
#42719 - Always attempt to restore widgets' previous assignment
#42867 - HTML Widget: toggleClass() should be passed true/false as second param