t/60: Ensured only the widget toolbar attached to the view element which is deepest in the view tree will show up

[oleq]

Suggested merge commit message (convention)

Fix: Ensured only the widget toolbar attached to the view element which is deepest in the view tree will show up. Code and documentation refactoring in the WidgetToolbarRepository. Closes ckeditor/ckeditor5#4595.

BREAKING CHANGE: The visibleWhen() function, a property of an object passed into WidgetToolbarRepository.register(), has been renamed to getRelatedElement() and must return an editing View element the toolbar should be attached to (instead of Boolean).

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Additional information

CI: https://github.com/ckeditor/ckeditor5/tree/t/ckeditor5-widget/60

Requires:

• t/ckeditor5-widget/60: Aligned to the new WidgetToolbarRepository API ckeditor5-image#269
• t/ckeditor5-widget/60: Aligned to the new WidgetToolbarRepository API ckeditor5-table#159
• t/ckeditor5-widget/60: Aligned to the new WidgetToolbarRepository API ckeditor5-media-embed#72

[coveralls]

Coverage remained the same at 100.0% when pulling 257040e on t/60 into dde537a on master.

[jodator]

Running tests locally:

yarn test -cws --files=widget,table,image,media-embed

I have one test failing:

[oleq]

It also fails on master so it's not related to this PR constellation.

[jodator]

Small docs fixes might be needed. Everything looks OK to me and works nicely :)

[oleq]

2 things that came to my mind:

1. @Mgsy, can you check out the constellation and see if the UX of the widget toolbars is OK?
2. s/getRelatedElement/getTargetElement? s/getRelatedElement/getAttachmentTarget?

[Mgsy]

@Mgsy, can you check out the constellation and see if the UX of the widget toolbars is OK?

LGTM 👍