fixing function ref

Author: Rolando Santamaria Maso

lib/server/low.js

@@ -92,7 +92,7 @@ class HttpRequest {
 
   getRawHeaders () {
     const raw = []
-    forEachObj(this.headers, (header, value) => {
+    forEach(this.headers, (header, value) => {
       raw.push(header, value)
     })
     return raw