Fix submit_form event not emitting when submitting a form (close #856)

Author: Paul Boocock

src/js/forms.js

@@ -97,7 +97,7 @@ export function FormTrackingManager(core, trackerId, contextAdder) {
   function getInnerFormElements(elt) {
     var innerElements = [];
     forEach(innerElementTags, function (tagname) {
-      var trackedChildren = elt.getElementsByTagName(tagname).filter(function (child) {
+      var trackedChildren = Array.prototype.filter.call(elt.getElementsByTagName(tagname), function (child) {
         return child.hasOwnProperty(trackingMarker);
       });
 

src/js/snowplow.js

@@ -129,7 +129,7 @@ export function Snowplow(asynchronousQueue, functionName) {
       do {
         now = new Date();
         if (
-          mutSnowplowState.outQueues.filter(function (queue) {
+          Array.prototype.filter.call(mutSnowplowState.outQueues, function (queue) {
             return queue.length > 0;
           }).length === 0
         ) {