Eliminated unused m_dragInitiator accessor to prevent dereferencing.
https://bugs.webkit.org/show_bug.cgi?id=37618

Patch by Abhishek Arya <inferno@chromium.org> on 2010-04-30
Reviewed by David Kilzer.

Test: editing/pasteboard/drag-drop-iframe-refresh-crash.html

* page/DragController.cpp:
(WebCore::DragController::tryDocumentDrag):
(WebCore::DragController::concludeEditDrag):
* page/DragController.h:
(WebCore::DragController::draggingImageURL):
(WebCore::DragController::documentUnderMouse):

LayoutTests: Tests for a crash when an image drag-drop operation happens inside a continuously refreshing iframe.
https://bugs.webkit.org/show_bug.cgi?id=37618

Patch by Abhishek Arya <inferno@chromium.org> on 2010-04-30
Reviewed by David Kilzer.

* editing/pasteboard/drag-drop-iframe-refresh-crash-expected.txt: Added.
* editing/pasteboard/drag-drop-iframe-refresh-crash.html: Added.
* editing/resources/drag-drop.html: Added.
* platform/qt/Skipped:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@58616 268f45cc-cd09-0410-ab3c-d52691b4dbfc