Widget Customizer: Remove jQuery.liveFilter dependency

[ocean90]

The search should do a better job. First pass attached.

• Moves search to collection
• Searches in description field too

[westonruter]

@ocean90: I love how the filter now matches against both the widget name and description, and how the order of the terms is irrelevant. Great idea on combining multiple lookahead patterns.

I found two issues:

1. The replacement of spaces was not done globally (needs / /g instead of ' '), so only the order of the first two words was not significant
2. The search term wasn't escaped for RegExp meta characters, so JavaScript errors could be thrown.

Here're my revisions on your patch: ​https://github.com/x-team/wordpress-develop/commit/95c146a718b72f13419776e6dc41daa09327cbba

Our patches combined: ​https://github.com/x-team/wordpress-develop/pull/3/files

[ocean90]

In 27650:

Widget Customizer: Improve widget search.

• Removes jQuery.liveFilter dependency
• Filters widget collection directly
• Widget's name, ID and description will be searched

fixes #27451.

[westonruter]

Filtering the widget collection turns out to cause some issues with adding multiple widgets of a certain instance, and also for sorting widgets in a widget area. Patch incoming...

[westonruter]

Update a search_matched property on the WidgetModel instead of filtering out widgets from availableWidgets; otherwise, the incremented multi_number gets lost, and only one instance of a multi-widget can be added. This also fixes a bug with a widget area losing its sortability after adding a widget via a search. Also, don't equate an empty array with an error when the instance is passed to the update_widget Ajax request. ​https://github.com/x-team/wordpress-develop/pull/9/files

[ocean90]

In 28044:

Widget Customizer: Fix widget filtering.

props westonruter.
fixes #27451.