Whoops. Missed this when adding the invalid string stuff.
Whoops. Missed this when adding the invalid string stuff.

svn path=/trunk/libcss/; revision=4663

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