Reviewed by Nikolas Zimmermann.

        https://bugs.webkit.org/show_bug.cgi?id=23587
        Refactor HitTestRequest to eliminate all the ugly boolean arguments and
        use an enum bitflag instead.  Cleanup all the code that constructs the
        various HitTestRequests to make the code more readable.

        * dom/Document.cpp:
        (WebCore::Document::elementFromPoint):
        (WebCore::Document::prepareMouseEvent):
        * editing/SelectionController.cpp:
        (WebCore::SelectionController::contains):
        * page/AccessibilityRenderObject.cpp:
        (WebCore::AccessibilityRenderObject::visiblePositionForPoint):
        (WebCore::AccessibilityRenderObject::doAccessibilityHitTest):
        * page/EventHandler.cpp:
        (WebCore::EventHandler::eventMayStartDrag):
        (WebCore::EventHandler::updateSelectionForMouseDrag):
        (WebCore::EventHandler::hitTestResultAtPoint):
        (WebCore::EventHandler::handleMousePressEvent):
        (WebCore::EventHandler::handleMouseDoubleClickEvent):
        (WebCore::EventHandler::handleMouseMoveEvent):
        (WebCore::EventHandler::handleMouseReleaseEvent):
        (WebCore::EventHandler::updateDragAndDrop):
        (WebCore::EventHandler::handleWheelEvent):
        (WebCore::EventHandler::sendContextMenuEvent):
        (WebCore::EventHandler::hoverTimerFired):
        (WebCore::EventHandler::handleDrag):
        * page/EventHandler.h:
        * rendering/HitTestRequest.h:
        (WebCore::HitTestRequest::):
        (WebCore::HitTestRequest::HitTestRequest):
        (WebCore::HitTestRequest::readOnly):
        (WebCore::HitTestRequest::active):
        (WebCore::HitTestRequest::mouseMove):
        (WebCore::HitTestRequest::mouseUp):
        (WebCore::HitTestRequest::ignoreClipping):
        * rendering/RenderFrameSet.cpp:
        (WebCore::RenderFrameSet::nodeAtPoint):
        * rendering/RenderLayer.cpp:
        (WebCore::RenderLayer::hitTest):
        (WebCore::RenderLayer::hitTestLayer):
        (WebCore::RenderLayer::updateHoverActiveState):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@40486 268f45cc-cd09-0410-ab3c-d52691b4dbfc