Fix #4046 - Last column disappearing upon edit

[imbalind]

I ran the tests and I got:

Failures: 1) ui-grid tutorial/103_filtering first grid on the page, filtered by male by default grid should have seven visible columns Message: Expected 8 to equal 7. 

which I have even without my changes.

Do I need to provide anything else?

[JLLeitschuh]

I don't understand what this is doing. I do know that that is a known failing test #4010 so you are all good on that front.

[imbalind]

What do you mean by:

I don't understand what this is doing.

?

[JLLeitschuh]

Basically I don't understand the code that you've modified. One of the other devs should take a look at this before merging. I don't feel like I understand that bit of the code well enough to add a LGTM.

[swalters]

This is being recorded in our application as well. I'm doing some research as to why this started happening. The code this addresses hasn't been touched in a very long time. Either this bug was always with us or something has changed elsewhere to cause this issue.

[swalters]

@imbalind thanks for the detailed issue and PR. I'm sure it would have taken me forever to even figure out how to recreate this bug.

[JLLeitschuh]

Closes #4046