fix: use parsePosition to parse background-position

Author: cdoublev

lib/properties/backgroundPosition.js

@@ -1,42 +1,14 @@
 'use strict';
 
-const { parseKeyword, parseLengthOrPercentage } = require('../parsers');
-
-var valid_keywords = ['top', 'center', 'bottom', 'left', 'right'];
-
-var parse = function parse(v) {
-  if (v === '') {
-    return undefined;
-  }
-  var parts = v.split(/\s+/);
-  if (parts.length > 2 || parts.length < 1) {
-    return undefined;
-  }
-  if (parts.length === 1) {
-    return parseLengthOrPercentage(parts[0]) || parseKeyword(parts[0], valid_keywords);
-  }
-  if (
-    parseLengthOrPercentage(parts[0]) !== undefined &&
-    parseLengthOrPercentage(parts[1]) !== undefined
-  ) {
-    return v;
-  }
-  if (
-    parseKeyword(parts[0], valid_keywords) === undefined ||
-    parseKeyword(parts[1], valid_keywords) === undefined
-  ) {
-    return undefined;
-  }
-  return v;
-};
+const { parsePosition } = require('../parsers');
 
 module.exports.isValid = function isValid(v) {
-  return parse(v) !== undefined;
+  return parsePosition(v) !== undefined;
 };
 
 module.exports.definition = {
   set: function(v) {
-    this._setProperty('background-position', parse(v));
+    this._setProperty('background-position', parsePosition(v));
   },
   get: function() {
     return this.getPropertyValue('background-position');