https://bugs.webkit.org/show_bug.cgi?id=69562

Source/WebCore: 

Some fake objects, like AXImageMapLink, have weak references to their parent's (since they are fake objects and
need some connection to the parent). However, if the parent disappears before the child, then we're left with a 
out of date reference to that parent.

The fix is to allow these elements to clear their parentage when the parent goes away.

Reviewed by Darin Adler.

Test: accessibility/image-map-update-parent-crash.html

* accessibility/AccessibilityMenuListOption.cpp:
(WebCore::AccessibilityMenuListOption::isVisible):
* accessibility/AccessibilityMenuListPopup.cpp:
(WebCore::AccessibilityMenuListPopup::isOffScreen):
(WebCore::AccessibilityMenuListPopup::isEnabled):
(WebCore::AccessibilityMenuListPopup::press):
(WebCore::AccessibilityMenuListPopup::addChildren):
(WebCore::AccessibilityMenuListPopup::childrenChanged):
* accessibility/AccessibilityMockObject.h:
(WebCore::AccessibilityMockObject::detachFromParent):
* accessibility/AccessibilityObject.cpp:
(WebCore::AccessibilityObject::clearChildren):
* accessibility/AccessibilityObject.h:
(WebCore::AccessibilityObject::detachFromParent):
* accessibility/AccessibilitySlider.cpp:
(WebCore::AccessibilitySliderThumb::elementRect):
* accessibility/AccessibilityTableColumn.cpp:
(WebCore::AccessibilityTableColumn::headerObjectForSection):

LayoutTests: 

Reviewed by Darin Adler.

* accessibility/image-map-update-parent-crash-expected.txt: Added.
* accessibility/image-map-update-parent-crash.html: Added.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@96973 268f45cc-cd09-0410-ab3c-d52691b4dbfc