Linked inline images can be added to table/image captions

[LukaszGudel]

Steps:

1. Add linked inline image.
2. Toggle table caption.
3. Drag&drop or copy&paste image into table caption.
4. Convert image to block.

CKE5-inline-linked-table-caption.mp4

Result:

Editor crashes with error:

writer.js:1489 Uncaught TypeError: Cannot read property 'getAttribute' of null
    at setAttributeOnItem (writer.js:1489)
    at Writer.removeAttribute (writer.js:421)
    at Object.callback (imagestylecommand.js:117)
    at Model._runPendingChanges (model.js:839)
    at Model.change (model.js:184)
    at ImageStyleCommand.execute (imagestylecommand.js:101)
    at ImageStyleCommand.<anonymous> (observablemixin.js:258)
    at ImageStyleCommand.fire (emittermixin.js:199)
    at ImageStyleCommand.<computed> [as execute] (observablemixin.js:262)
    at CommandCollection.execute (commandcollection.js:69)

Notes:

• this image needs to be linked as captions do not allow inserting nonlinked inline images
• linked image can be also inserted into image captions, but converting it to block will remove an image

[oleq]

Inline images should be blocked in all sorts of captions in MVP1. This is is a valid use-case, though (e.g. emoji-as-image).