Reviewed by Eric Seidel.

        Added Haiku-specific files for WebCore/page/.
        https://bugs.webkit.org/show_bug.cgi?id=26949

        Adding three new files, DragControllerHaiku.cpp, EventHandlerHaiku.cpp
        and FrameHaiku.cpp

        * page/haiku/DragControllerHaiku.cpp: Added.
        (WebCore::DragController::isCopyKeyDown):
        (WebCore::DragController::dragOperation):
        (WebCore::DragController::maxDragImageSize):
        (WebCore::DragController::cleanupAfterSystemDrag):
        * page/haiku/EventHandlerHaiku.cpp: Added.
        (WebCore::isKeyboardOptionTab):
        (WebCore::EventHandler::invertSenseOfTabsToLinks):
        (WebCore::EventHandler::tabsToAllControls):
        (WebCore::EventHandler::focusDocumentView):
        (WebCore::EventHandler::passWidgetMouseDownEventToWidget):
        (WebCore::EventHandler::passMouseDownEventToWidget):
        (WebCore::EventHandler::eventActivatedView):
        (WebCore::E...