validity assertion fails after removing a child of an <optgroup> element

https://bugs.webkit.org/show_bug.cgi?id=155720
<rdar://problem/27720746>

Reviewed by Brent Fulgham.

Source/WebCore:

All calls to HTMLSelectElement::setRecalcListItems also need to call HTMLSelectElement::updateValidity.

Test: fast/dom/HTMLSelectElement/select-remove-from-optgroup.html

* html/HTMLOptGroupElement.cpp:
(WebCore::HTMLOptGroupElement::recalcSelectOptions): Call 'updateValidity' after 'setRecalcListItems'.
* html/HTMLOptionElement.cpp:
(WebCore::HTMLOptionElement::insertedInto): Ditto.
* html/HTMLSelectElement.cpp:
(WebCore::HTMLSelectElement::parseAttribute): Ditto.

LayoutTests:

Add new test case that triggers a debug assertion when the HTMLSelectElement state
is not updated properly.

* fast/dom/HTMLSelectElement/select-remove-from-optgroup-expected.txt: Added.
* fast/dom/HTMLSelectElement/select-remove-from-optgroup.html: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@204186 268f45cc-cd09-0410-ab3c-d52691b4dbfc