Issues with using Backspace and Shift+Enter with the EnterKeyHandler plugin

[DJ Mountney]

IE7 and IE8 sometimes crashes when using shift enter in block elements, similar to bug #13697

And Firefox doesn't behave as expected when hitting backspace after a shift+enter in a block level element.

Chrome works as expected on 1.7.2 but on trunk has this bug: #15505

Steps to Repro for IE crash:

1. Use an editor with ViewSource? and EnterKeyHandling? (​http://jsfiddle.net/p4dmountney/ykrg2/)
2. Go Into Source Mode
3. Set value to <p>ab</p>
4. Set cursor at the end of the ab text
5. Hit Shift+Enter
6. Hit Backspace
7. Hit Shift+Enter
8. One more time, Backspace, and Shift+Enter

Expected Result: We should have one <br> after our ab

Actual Result: Sometimes it gives one br, sometimes it gives none, but more likely you won't be able to tell because the page will crash

In Firefox, doing the same steps, you will notice that backspace doesn't delete the br, it just seems to move the cursor.

The inconstancies make it hard to make a doh test for. I've attached the patch for the doh test I was working on for the IE crash. Patch is against trunk.

[DJ Mountney]

Trunk robot test patch

[dylan]

Moving all Editor tickets to 1.12 for now.

[dylan]

Ticket planning... move current 1.12 tickets out to 1.13 that likely won't get fixed in 1.12.