Refactor: Make getDocumentScrollTop a standalone function

pinry/static/js/helpers.js

@@ -81,3 +81,8 @@ function postPinData(data) {
 function getUrlParameter(name) {
     return decodeURIComponent((new RegExp('[?|&]' + name + '=' + '([^&;]+?)(&|#|;|$)').exec(location.search) || [, ""])[1].replace(/\+/g, '%20')) || null;
 }
+
+function getDocumentScrollTop() {
+    var doc = document.documentElement;
+    return (window.pageYOffset || doc.scrollTop)  - (doc.clientTop || 0);
+}

pinry/static/js/vue/main.js

@@ -348,11 +348,6 @@ Vue.component('pin-container', {
     bindScrollHandler: function () {
       var self = this;
 
-      function getDocumentScrollTop() {
-        var doc = document.documentElement;
-        return (window.pageYOffset || doc.scrollTop)  - (doc.clientTop || 0);
-      }
-
       scrollHandler = function() {
         if (self.status.loading || !self.status.hasNext) {
           return