MINOR Use of DropdownField in CMS should call setEmptyString instead of

use the $emptyString argument, as it's deprecated.

code/controllers/AssetAdmin.php

@@ -313,15 +313,15 @@ JS
 			'zip' => _t('AssetAdmin.AppCategoryArchive', 'Archive', 'A collection of files'),
 		);
 		$context->addField(
-			new DropdownField(
+			$typeDropdown = new DropdownField(
 				'q[AppCategory]',
 				_t('AssetAdmin.Filetype', 'File type'),
-				$appCategories,
-				null,
-				null,
-				' '
+				$appCategories
 			)
 		);
+
+		$typeDropdown->setEmptyString(' ');
+
 		$context->addField(
 			new CheckboxField('q[CurrentFolderOnly]', _t('AssetAdmin.CurrentFolderOnly', 'Limit to current folder?'))
 		);

code/controllers/CMSMain.php

@@ -284,19 +284,17 @@ class CMSMain extends LeftAndMain implements CurrentPageIdentifier, PermissionPr
 				_t('CMSMain.PAGES', 'Pages'),
 				$filterMap
 			),
-			new DropdownField(
+			$classDropdown = new DropdownField(
 				'q[ClassName]',
 				_t('CMSMain.PAGETYPEOPT','Page Type', 'Dropdown for limiting search to a page type'),
-				$pageTypes, 
-				null, 
-				null, 
-				_t('CMSMain.PAGETYPEANYOPT','Any')
+				$pageTypes
 			)
 			// new TextField('MetaTags', _t('CMSMain.SearchMetaTags', 'Meta tags'))
 		);
 		$dateGroup->subfieldParam = 'FieldHolder';
 		$dateFrom->setConfig('showcalendar', true);
 		$dateTo->setConfig('showcalendar', true);
+		$classDropdown->setEmptyString(_t('CMSMain.PAGETYPEANYOPT','Any'));
 
 		$actions = new FieldList(
 			FormAction::create('doSearch',  _t('CMSMain_left.ss.APPLY FILTER', 'Apply Filter'))