Fix by Mitz Pettel, reviewed by Darin.

    Fix by Mitz Pettel, reviewed by Darin.

        - fix http://bugzilla.opendarwin.org/show_bug.cgi?id=3438
          incorrect display of transparent 1x1 PNGs

        Test: fast/replaced/image-solid-color-with-alpha.html

        * platform/mac/ImageMac.mm:
        (WebCore::Image::checkForSolidColor): Changed to divide each color component
        by the alpha component. You need to do that since the bitmap context has
        premultiplied alpha but m_solidColor should be non-premultiplied.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@15758 268f45cc-cd09-0410-ab3c-d52691b4dbfc