[FIX] Allow for the iframe having been removed already

[StefanRijnhart]

When integrating ckeditor in Odoo, we encounter TypeError: iframe is null in http://localhost:9069/web_ckeditor4/static/lib/ckeditor/plugins/wysiwygarea/plugin.js:520 when the editor is created in a ajax popup. The editor is destroyed when the popup is closed, but by then the Odoo framework has already cleared out the DOM.

Same as #56, but I thought I'd try again.

[Reinmar]

I'm still a bit against just hiding an evidence of an issue rather than fixing the code (e.g. Odoo which should destroy CKEditor prior to destroying the DOM), but ok... let's see.

I would normally ask you for tests and some other improvements, but I want to have this researched on our side. My main doubt is whether new instances of the editor can be initialised after one of them is so ugly destroyed. Also, I want console logs notifying the developer that they destroyed CKEditor incorrectly, so this issue stays somehow visible.

We'll try to ship this in 4.5.3.

[StefanRijnhart]

Thanks @Reinmar for your response. On our side, we see no problems initializing new instances of the editor on the same page after destroying old ones with this patch.

[szymonkups]

Thanks for the PR. I've created separate ticket on Trac.
I've pushed new branch t/13790, it includes changes made in pull request plus additional test. It will be merged into master branch after the release of CKEditor 4.5.4 (which is currently in progress). I will close this PR after merge to the master branch.

[szymonkups]

Merged into master branch with ca91770.

[hongquanvn1998]

How to call ckeditor 4.x widget for field text in odoo ? thanks