Rework positionForCoordinates to be more efficient and to handle multi-column content.  This entailed
        adding a new field to HitTestResult called localPoint that cached the mouse coordinate in the coordinate
        space of the renderer.

        positionForCoordinates now takes local coordinates and so no longer needs to waste time recomputing
        absolute positions over and over again.

        Reviewed by darin

        * bridge/mac/WebCoreAXObject.mm:
        (-[WebCoreAXObject value]):
        (-[WebCoreAXObject doAXTextMarkerRangeForLine:]):
        (-[WebCoreAXObject doAXTextMarkerForPosition:]):
        * dom/Document.cpp:
        (WebCore::Document::prepareMouseEvent):
        * editing/SelectionController.cpp:
        (WebCore::SelectionController::contains):
        * editing/visible_units.cpp:
        (WebCore::previousLinePosition):
        (WebCore::nextLinePosition):
        * page/EventHandler.cpp:
        (WebCore::EventHandler::selectClosestWordFromMouseEvent):
        (WebCore::EventHandler::handleMousePressEventDoubleClick):
        (WebCore::EventHandler::handleMousePressEventTripleClick):
        (WebCore::EventHandler::handleMousePressEventSingleClick):
        (WebCore::EventHandler::handleMouseMoveEvent):
        (WebCore::EventHandler::handleMouseReleaseEvent):
        (WebCore::EventHandler::sendContextMenuEvent):
        * page/EventHandler.h:
        * page/MouseEventWithHitTestResults.cpp:
        (WebCore::MouseEventWithHitTestResults::MouseEventWithHitTestResults):
        * page/MouseEventWithHitTestResults.h:
        (WebCore::MouseEventWithHitTestResults::localPoint):
        * page/mac/WebCoreFrameBridge.mm:
        (-[WebCoreFrameBridge _visiblePositionForPoint:]):
        * rendering/EllipsisBox.cpp:
        (WebCore::EllipsisBox::nodeAtPoint):
        * rendering/HitTestResult.h:
        (WebCore::HitTestResult::localPoint):
        (WebCore::HitTestResult::setLocalPoint):
        * rendering/InlineFlowBox.cpp:
        (WebCore::InlineFlowBox::nodeAtPoint):
        * rendering/InlineTextBox.cpp:
        (WebCore::InlineTextBox::nodeAtPoint):
        * rendering/RenderBlock.cpp:
        (WebCore::RenderBlock::nodeAtPoint):
        (WebCore::RenderBlock::hitTestContents):
        (WebCore::RenderBlock::positionForCoordinates):
        * rendering/RenderBox.cpp:
        (WebCore::RenderBox::nodeAtPoint):
        * rendering/RenderContainer.cpp:
        (WebCore::RenderContainer::positionForCoordinates):
        * rendering/RenderFlow.cpp:
        (WebCore::RenderFlow::hitTestLines):
        * rendering/RenderInline.cpp:
        (WebCore::RenderInline::positionForCoordinates):
        * rendering/RenderLayer.cpp:
        (WebCore::RenderLayer::autoscroll):
        (WebCore::RenderLayer::hitTestLayer):
        * rendering/RenderObject.cpp:
        (WebCore::RenderObject::updateHitTestResult):
        * rendering/RenderObject.h:
        * rendering/RenderPath.cpp:
        (WebCore::RenderPath::nodeAtPoint):
        * rendering/RenderReplaced.cpp:
        (WebCore::RenderReplaced::positionForCoordinates):
        * rendering/RenderTableRow.cpp:
        (WebCore::RenderTableRow::nodeAtPoint):
        * rendering/RenderTableSection.cpp:
        (WebCore::RenderTableSection::nodeAtPoint):
        * rendering/RenderText.cpp:
        (WebCore::RenderText::positionForCoordinates):
        * rendering/RootInlineBox.cpp:
        (WebCore::RootInlineBox::nodeAtPoint):
        (WebCore::RootInlineBox::closestLeafChildForXPos):
        * rendering/RootInlineBox.h:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@18758 268f45cc-cd09-0410-ab3c-d52691b4dbfc