ss4upgrade: Fixed loading of resources in CMS

Author: adunn

_config/config.yml

@@ -0,0 +1,10 @@
+---
+Name: dropdownimagefield
+---
+
+SilverStripe\Admin\LeftAndMain:
+  extra_requirements_javascript:
+    - 'copperis/dropdownimagefield: javascript/Polyfill.js'
+    - 'copperis/dropdownimagefield: javascript/ImageSelect.jquery.js'
+  extra_requirements_css:
+    - 'copperis/dropdownimagefield: css/ImageSelect.css'

code/DropdownImageField.php

@@ -26,12 +26,6 @@ public function __construct($name, $title, $sourceObject, $keyField = 'ID', $lab
     public function Field($properties = array()) {
 
         $dirName = basename(dirname(dirname(__FILE__)));
-        ;
-
-        Requirements::javascript('copperis/dropdownimagefield: javascript/Polyfill.js');
-        Requirements::javascript('copperis/dropdownimagefield: javascript/ImageSelect.jquery.js');
-        Requirements::css('copperis/dropdownimagefield: css/ImageSelect.css');
-
         $source = $this->getSource();
         $options = array();
         if ($source) {