[IE10] Wrong cursor position after enter BR

[Garry Yao]

1. Load any sample page with enter mode as BR;
2. Clear all content, type some chars
3. Enter key pressed twice

• Actual: Cursor moves to the second line;
• Expected: Cursor moves to the third line;

[Garry Yao]

Besides, enter key in preformatted is also partially broken as cursor is not moving to the next line.

[Garry Yao]

Opened t/9535 for review.

[Garry Yao]

The ticket tc on IE10, depends on the result of retrieving the following selection range:

foo
<br />^
bar

Which incorrectly returns the range anchored before BR element.

We had ​conversation before regard switching to W3C DOM selection, but had been worried about the stabality.

For now the suite of ​selection test has established, it's less risky to consider this change, at least for IE10.

The patch proposed this change for IE10 only, as it eliminates several selection regard quirks like the ticket tc, the tests results are passing and I did some manual tests to verify it.

[Garry Yao]

It's revealed on #9535 another IE bug when using old MS selection API, once BR is contained inside of text selection from right-to-left, this time on IE9 as well, so it would be well worthy to consider IE9 on subject of this change as well.

[Garry Yao]

The selection change is ​masterised, now the ticket branch contains only the patch for fix inside of <pre>.

[Piotrek Koszuliński]

I couldn't test IE10, but I haven't found regressions on other browsers.

[Garry Yao]

Fixed on master with:

​https://github.com/ckeditor/ckeditor-dev/commit/7d66fdda897612a2c7521616820e3282c394304f