Make m_offset private and change all callers to use deprecatedEditingOffset().
        https://bugs.webkit.org/show_bug.cgi?id=25472

        Per Darin's suggestion, this was just a simple search replace
        of .m_offset with .deprecatedEditingOffset().

        There was one change in InsertParagraphSeparatorCommand::doApply to use
        Position::moveToOffset(0) instead of .m_offset = 0;

        * dom/Position.cpp:
        (WebCore::Position::rendersInDifferentPosition):
        (WebCore::Position::leadingWhitespacePosition):
        * dom/Position.h:
        (WebCore::Position::deprecatedEditingOffset):
        (WebCore::Position::moveToOffset):
        (WebCore::operator==):
        * dom/PositionIterator.h:
        (WebCore::PositionIterator::PositionIterator):
        * dom/Range.cpp:
        (WebCore::Range::create):
        (WebCore::Range::compareBoundaryPoints):
        * editing/ApplyStyleCommand.cpp:
        (WebCore::ApplyStyleCommand::applyRela...