* Mark a widget as dirty when a field input triggers a `change` or `input` event; clear dirty state when widget is successfully saved.
* Disable Save button and re-label "Saved" when widget not dirty.
* Show AYS dialog when leaving widgets admin screen with unsaved changes.
* When widgets are dirty, expand all unsaved widgets at AYS check and focus on first one.
* Change "Close" link to "Done"; hide link when widget is dirty and reveal when saved.
* The "Done" link persistently appears in the Customizer even after making a change (when the widget is dirty) because changes are autosaved into the changeset.
* Prevent saving widget when form fails `checkValidity`.
* Fix frequency of triggering of `change` event on the rich Text widget's `textarea` limited now to when there are actual changes.
* Add a class of `widget-dirty` to widget containers when the widget has unsaved changes.
Props westonruter, timmydcrawford, melchoyce.
Fixes#41610, #23120.
Built from https://develop.svn.wordpress.org/trunk@41352
git-svn-id: http://core.svn.wordpress.org/trunk@41185 1a063a9b-81f0-0310-95a4-ce76da25c4cd
The Text widget in legacy mode omits TinyMCE and retains old behavior for matching pre-existing Text widgets. Usage pointers added to default visual mode appear when attempting to paste HTML code into the Visual tab and when clicking on the Text tab, informing users of the new Custom HTML widget.
Props westonruter, melchoyce, gitlost for testing, obenland for testing, dougal for testing, afercia for testing.
See #35243.
Fixes#40951.
Built from https://develop.svn.wordpress.org/trunk@41050
git-svn-id: http://core.svn.wordpress.org/trunk@40900 1a063a9b-81f0-0310-95a4-ce76da25c4cd
