Reviewed by Eric Seidel.

        Stop instantiating legacy editing positions in InsertTextCommand, MoveSelectionCommand,
        ReplaceSelectionCommand, SelectionController, SpellChecker, TypingCommand, and markup.cpp
        https://bugs.webkit.org/show_bug.cgi?id=52676

        Stop instantiating legacy editing positions in the following files.

        * editing/InsertTextCommand.cpp:
        (WebCore::InsertTextCommand::prepareForTextInsertion):
        (WebCore::InsertTextCommand::performTrivialReplace):
        (WebCore::InsertTextCommand::input):
        (WebCore::InsertTextCommand::insertTab):
        * editing/MoveSelectionCommand.cpp:
        (WebCore::MoveSelectionCommand::doApply):
        * editing/ReplaceSelectionCommand.cpp:
        (WebCore::ReplaceSelectionCommand::removeUnrenderedTextNodesAtEnds):
        (WebCore::ReplaceSelectionCommand::mergeEndIfNeeded):
        (WebCore::ReplaceSelectionCommand::doApply):
        (WebCore::ReplaceSelectionCommand::shouldRemoveEndBR):
        (WebCore::ReplaceSelectionCommand::performTrivialReplace):
        * editing/SelectionController.cpp:
        (WebCore::SelectionController::setSelectionFromNone):
        * editing/SpellChecker.cpp:
        (WebCore::SpellChecker::didCheck):
        * editing/TypingCommand.cpp:
        (WebCore::TypingCommand::makeEditableRootEmpty):
        (WebCore::TypingCommand::deleteKeyPressed):
        (WebCore::TypingCommand::forwardDeleteKeyPressed):
        * editing/markup.cpp:
        (WebCore::StyledMarkupAccumulator::appendText):
        (WebCore::StyledMarkupAccumulator::serializeNodes):
        (WebCore::highestAncestorToWrapMarkup):
        (WebCore::createMarkup):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@76560 268f45cc-cd09-0410-ab3c-d52691b4dbfc