Fix font shorthand parser to reject spurious instances of inherit
Fix font shorthand parser to reject spurious instances of inherit

svn path=/trunk/libcss/; revision=8069

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