Test cases for illegal values.
Test cases for illegal values.

svn path=/trunk/libcss/; revision=6153

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