AX: If an element that is a continuation is removed, its parent tree is not notified appropriately that their children have changed
https://bugs.webkit.org/show_bug.cgi?id=41000

Reviewed by Darin Adler.

WebCore: 

Test: accessibility/removed-continuation-element-causes-crash.html

* accessibility/AccessibilityObject.h:
(WebCore::AccessibilityObject::updateChildrenIfNecessary):
* accessibility/AccessibilityRenderObject.cpp:
(WebCore::AccessibilityRenderObject::childrenChanged):
(WebCore::AccessibilityRenderObject::addChildren):
* accessibility/AccessibilityRenderObject.h:

LayoutTests: 

* accessibility/removed-continuation-element-causes-crash-expected.txt: Added.
* accessibility/removed-continuation-element-causes-crash.html: Added.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@61622 268f45cc-cd09-0410-ab3c-d52691b4dbfc