On IE11, style="overflow-x: auto" becomes -ms-overflow-x when switching between source and wysiwyg

[Peter Storey]

Steps to reproduce

1. Open a ckeditor in IE11
2. In source view, add <div style="overflow-x:auto"></div>
3. Switch to editor view then back to source view

Expected result

<div style="overflow-x:auto">

Actual result

<div style="-ms-overflow-x:auto">

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

allowedContent = true;

extra plugins: colordialog, oembed, widget, aviary, nanospell

Still happens if the div has contents within it

I've tried this on 4.6.1, 4.6.2 and 4.4.2 and it happens the same.

We have a data processor with .toHtml and .toDataFormat methods, however logging out at various points of each, it is still overflow-x on the last line of .toHtml and comes to .toDataFormat as -ms-overflow-x. Commenting out the entire data processor causes the bug to persist.

[kkrzton]

Happens on IE10, IE11. Tested on ​http://sdk.ckeditor.com/samples/fullpreset.html. Might be connected with styles normalization (using native approach) while switching modes.

[kkrzton]

See ​https://github.com/ckeditor/ckeditor-dev/issues/682#issuecomment-318278303.