Improvement of fix #177

[dmarchuk]

Improves 6d48805 with comment from @Jekedorff. Sending PR so the fix could get to master branch ASAP.

[arendjr]

Can you tell me what this improvement does, exactly? The original comment said that fromElement might not be properly supported across browsers, but so far I've noticed no issue. I found some documentation suggesting Firefox might be the only browser not supporting fromElement, but I've tested it with Firefox and scrolling seems to work fine (Linux).

Also, this fix is quite hard to understand and seems rather brittle, so it would likely break again in the future. I wouldn't merge this without further evidence of browser support and an improvement to make this fix more robust and understandable.

[dmarchuk]

The original comment mentions that because FF doesn't have property fromElement, suggested fix (which is already in the master branch) causes selectivity dropdown being still open when bluring the input or dropdown itself. So now the only way to close the dropdown in FF is to click again on the input itself. Recordings proving the bug in FF: Mac and Windows.

Also, this fix is quite hard to understand and seems rather brittle, so it would likely break again in the future.

You are definitely right, I've made an improvement to the if statement so it's more transparent, understandable and cleaner in 7216241. I also added a comment there. I used contains() method and relatedTarget property - both are supported in all major browsers.

Recordings prooving fix of the bug in FF: Mac and Windows.

Tested on:
Windows: Edge 15, IE11, FF53, Chrome 58, Opera 45
Mac: Safari 10, FF53, Chrome 58, Opera 45

[arendjr]

I see, I indeed missed the fact the dropdown had become hard to close on Firefox.

This fix indeed also seems much more robust this way, thanks!