Move RangeBoundaryPoint off of Position, per Darin's suggestion
        https://bugs.webkit.org/show_bug.cgi?id=24966

        Rename setToChild to setToBeforeChild (since that's what the method does)

        * dom/Position.h:
        (WebCore::Position::offsetInContainerNode):
        * dom/Range.cpp:
        (WebCore::Range::insertNode):
        (WebCore::Range::selectNodeContents):
        (WebCore::boundaryNodeWillBeRemoved):
        * dom/Range.h:
        (WebCore::Range::startPosition):
        (WebCore::Range::endPosition):
        * dom/RangeBoundaryPoint.h:
        (WebCore::RangeBoundaryPoint::RangeBoundaryPoint):
        (WebCore::RangeBoundaryPoint::container):
        (WebCore::RangeBoundaryPoint::childBefore):
        (WebCore::RangeBoundaryPoint::position):
        (WebCore::RangeBoundaryPoint::offset):
        (WebCore::RangeBoundaryPoint::clear):
        (WebCore::RangeBoundaryPoint::set):
        (WebCore::RangeBoundaryPoint::setOffset):
        (WebCore::RangeBoundaryPoint::setToBeforeChild):
        (WebCore::RangeBoundaryPoint::setToStartOfNode):
        (WebCore::RangeBoundaryPoint::setToEndOfNode):
        (WebCore::RangeBoundaryPoint::childBeforeWillBeRemoved):
        (WebCore::RangeBoundaryPoint::invalidateOffset):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@42264 268f45cc-cd09-0410-ab3c-d52691b4dbfc