AX: Move addChildren, addChild, insertChild, canHaveChildren, setNeedsToUpdateChildre...

AX: Move addChildren, addChild, insertChild, canHaveChildren, setNeedsToUpdateChildren, setNeedsToUpdateSubtree, clearChildren, and needsToUpdateChildren out of AXCoreObject interface
https://bugs.webkit.org/show_bug.cgi?id=237801

Reviewed by Andres Gonzalez.

All of these virtual methods are ASSERT_NOT_REACHED no-ops for AXIsolatedObjects,
so this patch moves them to AccessibilityObject.h instead.

* accessibility/AccessibilityObject.h:
(WebCore::AccessibilityObject::addChildren):
(WebCore::AccessibilityObject::canHaveChildren const):
(WebCore::AccessibilityObject::setNeedsToUpdateChildren):
(WebCore::AccessibilityObject::setNeedsToUpdateSubtree):
(WebCore::AccessibilityObject::needsToUpdateChildren const):
* accessibility/AccessibilityObjectInterface.h:
* accessibility/isolatedtree/AXIsolatedObject.cpp:
(WebCore::AXIsolatedObject::addChildren): Deleted.
(WebCore::AXIsolatedObject::addChild): Deleted.
(WebCore::AXIsolatedObject::insertChild): Deleted.
(WebCore::AXIsolatedObject::canHaveChildren const): Deleted.
(WebCore::AXIsolatedObject::setNeedsToUpdateChildren): Deleted.
(WebCore::AXIsolatedObject::setNeedsToUpdateSubtree): Deleted.
(WebCore::AXIsolatedObject::clearChildren): Deleted.
(WebCore::AXIsolatedObject::needsToUpdateChildren const): Deleted.
* accessibility/isolatedtree/AXIsolatedObject.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@291237 268f45cc-cd09-0410-ab3c-d52691b4dbfc