Fix a bug where background-position truncates instead of rounding when it evaluates to fractional
        pixel values.  This matches other browsers.

        Reviewed by maciej

        Added fast/backgrounds/background-position-rounding.html

        * rendering/Length.h:
        (WebCore::Length::calcValue):
        (WebCore::Length::calcMinValue):
        * rendering/RenderBox.cpp:
        (WebCore::RenderBox::calculateBackgroundImageGeometry):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@31389 268f45cc-cd09-0410-ab3c-d52691b4dbfc