Add support for validation to EuiComboBox and fix some bugs

[cjcenizal]

No description provided.

[cjcenizal]

@snide Do you see any problem with this changing to fixed? Is there a reason it needs to be absolute?

[snide]

What happens when you scroll the page? Fixed normally breaks in that situation if it's open unless you are constantly calculating it on scroll.

[cjcenizal]

We update the position as the user scrolls

[snide]

Looks like you're constantly calculating so you should be ok. Lemme double check on IE11 though.

[snide]

Little laggy on IE11 but seems acceptable. FWIW it's broken on master in a similar way to the tooltips (where the top value isn't being applied correctly).

[snide]

I'll do some more review tonight, but off-hand I think this works fine. Checked the other browsers as well.

[cjcenizal]

@snide Thanks for taking a look. That scroll lag in IE11 is pretty gnarly. I figured out a way to fix the original bug using position: absolute and removing the scroll listener, so hopefully that lag is addressed now.

[snide]

@cjcenizal Think that brought in a new issue.

FWIW this looks like a similar problem to the calc on master, where top isn't getting a correct value. On master it just ends up at the bottom of body because it isn't set. Here it looks like it's getting a 0.

[cjcenizal]

@snide Is top being set inside the element's style attribute? I just pushed a change which will also apply !important to the inline style, but that shouldn't be necessary since it should have higher specificity than the class already.

[snide]

@cjcenizal nope. for some reason your style top value doesn't get calculated. This is the same issue I noticed on #610, so my guess is that it has to do with calculatePopoverPosition but I haven't dug in too deep on your code.

[cjcenizal]

@snide Thanks, I created #633 to capture this bug so we can address it later.