fix(hint): properly clean up when location is changed before DOM content has been loaded

The `beforeunload` event was never fired is the location was changed before the DOM content had
been loaded (e.g. directly inside a `<script>` tag. The `unload` event is fired more consistently.

Fixes angular/batarang#290

Author: gkalpak

hint.js

@@ -54,7 +54,7 @@ else {
   /* angular should remove DEFER_LABEL from window.name, but if angular is never loaded, we want
    to remove it ourselves, otherwise hint will incorrectly detect protractor as being present on
    the next page load */
-  window.addEventListener('beforeunload', function() {
+  window.addEventListener('unload', function() {
     if (deferRegex.test(window.name)) {
       window.name = window.name.substring(DEFER_LABEL.length);
     }