Make rgb() parsing work.
Make rgb() parsing work.

svn path=/trunk/libcss/; revision=6042

prepare/netsurf_libcss,prepare/netsurf_libcss,zhuyadong/libcss,servo/libcss,zhuyadong/libcss,servo/libcss,prepare/netsurf_libcss,zhuyadong/libcss,servo/libcss