Select element gets 'duplicated' in FireFox

[Jakub Ś]

Paste the folowing code:

<form action="formAct" id="myid" method="get" name="form">
	<select name="myselect" size="1"><option selected="selected" value="val1">opt1</option><option value="val2">opt2</option><option value="val3">opt3</option></select></form>
<p>
	<select name="myselect" size="1"><option selected="selected" value="val1">opt1</option><option value="val2">opt2</option><option value="val3">opt3</option></select></p>

1. Place the cursor after select element in form and press enter

Result: seceond empty select element is created.

Bugs #7502 #7503 describe issues with select and eneter key for other browsers.

[Jakub Ś]

Problem can be reproduced in CKEditor 4.4.7 in Firefox and Blink browsers.