[Edge] Dropped support for `setActive` (used to focus editor in some cases).

[kkrzton]

The parent task is #14819.

The newest version of Edge browser (Edge 38.14393, EdgeHTML 14.14393) dropped support for setActive which ​is used to focus editor in some cases (e.g. divarea plugin) to ​prevent unwanted scrolling.

While focus should be probably used in this case, it causes this unwanted scrolling so some workaround should be also applied.

Steps to reproduce

1. Go to plugins/divarea/samples/divarea.html.
2. Run CKEDITOR.instances.editor1.editable().find('table').getItem(0).scrollIntoView() in the console.
3. Run CKEDITOR.instances.editor1.focus() in the console.

To check if editor was focused use document.activeElement.

Expected result

Editor should be focused without scrolling.

Actual result

Editor is focused and scrolled to the top.

Other details (browser, OS, CKEditor version, installed plugins)

Edge (Edge 38.14393, EdgeHTML 14.14393)

---

This issue causes some unit tests fails in:

• tests/core/config/inline
• tests/core/dom/documentfragment
• tests/core/editable/domfix2
• tests/core/editable/wysiwyg
• tests/core/editor/title
• tests/core/filter/editor
• tests/core/selection/editor
• tests/core/selection/fake
• tests/plugins/autoembed/autoembednotifications
• tests/plugins/floatingspace/floatingspace
• tests/plugins/image/image
• tests/plugins/mathjax/mathjax-mock
• tests/plugins/pastefromword/pastefromword
• tests/plugins/sourcearea/source
• tests/plugins/uploadimage/uploadimage
• tests/tickets/11500/1

At least using focus (instead of setActive) fixes the tests but scrolling problem remains.

[kkrzton]

After further investigating this issue it seems that not the native focus is the reason of unwanted scrolling (​http://jsfiddle.net/f1ames/v1bbspoe/) but some custom focus post-logic.

[kkrzton]

This one was a little tricky to track, but:

• The scrolling is caused by a native focus call (not by a custom logic as I assumed in a previous comment).
• The scrolling effect does not occur when debugging via dev console (active breakpoints - pausing the code execution).
• The scrolling occurs only when focus is executed via code (not initiated by user interaction) - that's why here ​http://jsfiddle.net/f1ames/v1bbspoe/1 clicking button does not cause scrolling but timeout call does.
• The scroll caused by focus happens in async way so the new scrollTop value should be retrieved in a deferred way after focus is called.

[kkrzton]

Pushed fix to ​t/14825.

One thing to notice is that the scroll happens only if editor is focused for the first time. If it was focused before, refocusing works as expected.

[Tomasz Jakut]

Fixed with ​git:3f95046.