2011-07-08 Simon Fraser <simon.fraser@apple.com>

      Clean up RenderWidget::destroy() to share more code
        https://bugs.webkit.org/show_bug.cgi?id=64138

        Reviewed by James Robinson.

        RenderWidget::destroy() copied code from various other
        destroy() methods, which made code maintenance in this
        area very risky.

        Fix by adding a virtual willBeDestroyed() method, which
        replaces most instances of destroy(). Now, only RenderWidget
        and RenderObject implement destroy(), and each just calls
        willBeDestroyed(). Code duplication is averted.

        No behavior change, so no tests.

        * rendering/RenderBlock.cpp:
        (WebCore::RenderBlock::willBeDestroyed):
        * rendering/RenderBlock.h:
        * rendering/RenderBox.cpp:
        (WebCore::RenderBox::willBeDestroyed):
        * rendering/RenderBox.h:
        * rendering/RenderBoxModelObject.cpp:
        (WebCore::RenderBoxModelObject::willBeDestroyed):
        * rendering/RenderBoxModelObject.h:
        * rendering/RenderFullScreen.cpp:
        (RenderFullScreenPlaceholder::willBeDestroyed):
        (RenderFullScreen::willBeDestroyed):
        * rendering/RenderFullScreen.h:
        * rendering/RenderInline.cpp:
        (WebCore::RenderInline::willBeDestroyed):
        * rendering/RenderInline.h:
        * rendering/RenderListItem.cpp:
        (WebCore::RenderListItem::willBeDestroyed):
        * rendering/RenderListItem.h:
        * rendering/RenderObject.cpp:
        (WebCore::RenderObject::willBeDestroyed):
        (WebCore::RenderObject::destroy):
        * rendering/RenderObject.h:
        * rendering/RenderReplaced.cpp:
        (WebCore::RenderReplaced::willBeDestroyed):
        * rendering/RenderReplaced.h:
        * rendering/RenderTableCell.cpp:
        (WebCore::RenderTableCell::willBeDestroyed):
        * rendering/RenderTableCell.h:
        * rendering/RenderTableRow.cpp:
        (WebCore::RenderTableRow::willBeDestroyed):