Customize: Nav menu items should preview using original object title if not title supplied

[westonruter]

In wp_setup_nav_menu_item() there is logic to set the nav menu item's title to be the original post or term's title if no title is supplied. This logic is not getting applied when previewing in the customizer, however.

[celloexpressions]

Nice catch! Tested and the patch looks ready to commit to me.

[westonruter]

@celloexpressions I found a couple other situations where original_title wasn't being used.

1. Original title wasn't being used as the control title.
2. Original title wasn't being used as a placeholder for the nav label input field.

And then the original title was being used where it shouldn't, namely when loading the customizer when a nav menu item that had an empty title it would get populate with the original title. So you could save the customizer with a blank title and then reload the customizer and you'd see the navigation label no longer empty.

See 38015.1.diff​

[celloexpressions]

Looks good to me with those additional fixes.

[westonruter]

In 38618:

Customize: Ensure nav menu items lacking a label use the title from the original object.

Use original title as placeholder for label and in control title. Prevent original title from overriding empty label in initial setting values.

Fixes #38015.

[westonruter]

In 39393:

Customize: Fix handling of the nav menu item labels (titles) that match defaults (original titles) and fix the display of item type labels.

• Show default labels for nav menu item as placeholders in a control's label field instead of showing blank.
• Store empty string as label instead of copying default labels.
• Prevent labels for post type archive items from being dropped in preview.
• Also ensure that the item type label is displayed on nav menu item controls for settings that are loaded from an existing changeset.

Amends [38618].
See #38015.
Fixes #38955.

[westonruter]

In 39395:

Customize: Fix handling of the nav menu item labels (titles) that match defaults (original titles) and fix the display of item type labels.

• Show default labels for nav menu item as placeholders in a control's label field instead of showing blank.
• Store empty string as label instead of copying default labels.
• Prevent labels for post type archive items from being dropped in preview.
• Also ensure that the item type label is displayed on nav menu item controls for settings that are loaded from an existing changeset.

Amends [38618].
See #38015.
Fixes #38955 for 4.7 branch.

[westonruter]

In 39994:

Customize: Trim whitespace from nav menu item titles so that the underlying object's original title appears as input placeholder and in the control's title.

Whitespace is trimmed from titles in PHP when saved in any case, so this aligns the client-side behavior with what happens on the server.

Amends [38618].
See #38015.
Fixes #39600.

[dd32]

In 40094:

Customize: Trim whitespace from nav menu item titles so that the underlying object's original title appears as input placeholder and in the control's title.

Whitespace is trimmed from titles in PHP when saved in any case, so this aligns the client-side behavior with what happens on the server.

Amends [38618].
Merges [39994] to the 4.7 branch.
See #38015.
Fixes #39600.