Cursor gets stuck in inline widget

[Gert Sallaerts]

Steps to reproduce

1. Go to ​http://sdk.ckeditor.com/samples/placeholder.html
2. Start a new paragraph by placing the cursor after "hours." and pressing enter
3. Click the insert placeholder button in toolbar, type "test", click ok to instert
4. Place the cursor below the placeholder, so it's somewhere in the middle under the placeholder on the next line (after "Sh" for example)
5. Press up key on keyboard

Expected result

Cursor is either in front of the placeholder widget or skips it and jumps to the line above.

Actual result

• Cursor is stuck. Inside the placeholder I think, because the bottom bar displays: "body p placeholder"
• You can't move the cursor using the arrow keys, nor can you type in any text
• You have to use the mouse and click somewhere to be able to continue editing

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

• OSX 10.11
• Chrome 57.0.2987.110 (64-bit)
• Safari 10.1 (11603.1.30.0.34)