- fix <rdar://problem/3109180> VIP: after go back, page jumps after loading even if I scrolled while loading

        * history/CachedPage.cpp: (WebCore::CachedPage::clear): Call clearFrame rather than
        clearPart -- the "part" term was leftover prehistoric terminology.

        * loader/FrameLoader.cpp:
        (WebCore::FrameLoader::open): Call setWasScrolledByUser(false) on the page, so that we
        can detect any user scrolling that happens during the "go back" process.
        (WebCore::FrameLoader::restoreScrollPositionAndViewState): Don't scroll if the view's
        wasScrolledByUser flag is set.
        (WebCore::FrameLoader::loadItem): Call setWasScrolledByUser(false) false when we do
        a new "load" (actually just a scroll) using the same frame. Also moved the line of code that
        sets m_currentHistoryItem to make this code path mroe similar to recursiveGoToItem.
        (WebCore::FrameLoader::recursiveGoToItem): Ditto.

        * page/Frame.cpp:
        (WebCore::Frame::~Frame): Call clearFrame rather than stting m_frame directly.
        (WebCore::Frame::sendScrollEvent): Call setWasScrolledByUser(true) on FrameView. The FrameView
        itself knows to ignore this if the scrolling is being done programmatically instead of by the user.

        * page/FrameView.h: Added wasScrolledByUser and setWasScrolledByUser. Also removed unneeded
        include and class forward declarations, renamed clearPart to clearFrame, removed uneeded function
        haveDelayedLayoutScheduled, and removed unneeded friend declarations.
        * page/FrameView.cpp:
        (WebCore::FrameViewPrivate::FrameViewPrivate): Added m_inProgrammaticScroll and m_wasScrolledByUser.
        (WebCore::FrameViewPrivate::reset): Set m_wasScrolledByUser to false.
        (WebCore::FrameView::clearFrame): Renamed from clearPart.
        (WebCore::FrameView::scrollRectIntoViewRecursively): Added code to set the m_inProgrammaticScroll flag.
        (WebCore::FrameView::setContentsPos): Ditto.
        (WebCore::FrameView::wasScrolledByUser): Added.
        (WebCore::FrameView::setWasScrolledByUser): Added. Does nothing if called when m_inProgrammaticScroll
        is true.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@21454 268f45cc-cd09-0410-ab3c-d52691b4dbfc