fix some browser bugs

Author: hacdias

src/core/runtime/dns-browser.js

@@ -10,11 +10,13 @@ module.exports = (domain, opts, callback) => {
 
   window.fetch(url, {mode: 'cors'})
     .then((response) => {
-      const resp = response.json()
-      if (resp.Path) {
-        return callback(null, resp.Path)
+      return response.json()
+    })
+    .then((response) => {
+      if (response.Path) {
+        return callback(null, response.Path)
       } else {
-        return callback(new Error(resp.Message))
+        return callback(new Error(response.Message))
       }
     })
     .catch((error) => {