Fix top property always clamped to 0

This regressed in c06fbab. Fixes #281. Test: jsdom/jsdom#4012.

Author: asamuzaK

lib/properties/top.js

@@ -15,7 +15,6 @@ module.exports.parse = (v, opt = {}) => {
   });
   if (Array.isArray(value) && value.length === 1) {
     return parsers.resolveNumericValue(value, {
-      min: 0,
       type: "length"
     });
   } else if (typeof value === "string") {