fix: try fix for old node

Author: Scrum

index.js

@@ -2,6 +2,7 @@
 
 var htmlparser = require('htmlparser2');
 var isObject = require('isobject');
+var objectAssign = require('object-assign');
 
 /**
  * @see https://github.com/fb55/htmlparser2/wiki/Parser-options
@@ -49,7 +50,7 @@ function postHTMLParser(html, options) {
         Object.keys(attrs).forEach(function(key) {
             var obj = {};
                 obj[key] = attrs[key].replace(/"/g, '"');
-            Object.assign(result, obj);
+            objectAssign(result, obj);
         });
 
         return result;

package.json

@@ -26,7 +26,8 @@
   "homepage": "https://github.com/posthtml/posthtml-parser#readme",
   "dependencies": {
     "htmlparser2": "^3.9.2",
-    "isobject": "^2.1.0"
+    "isobject": "^2.1.0",
+    "object-assign": "^4.1.1"
   },
   "devDependencies": {
     "chai": "^3.3.0",