Upgrade usage of global methods

code/Controllers/CMSMain.php

@@ -7,6 +7,7 @@ use SilverStripe\Admin\CMSBatchActionHandler;
 use SilverStripe\Admin\LeftAndMain_SearchFilter;
 use SilverStripe\Admin\LeftAndMainFormRequestHandler;
 use SilverStripe\CMS\Model\VirtualPage;
+use SilverStripe\Core\Environment;
 use SilverStripe\Forms\Tab;
 use SilverStripe\ORM\CMSPreviewable;
 use SilverStripe\Admin\LeftAndMain;
@@ -1883,8 +1884,8 @@ class CMSMain extends LeftAndMain implements CurrentPageIdentifier, PermissionPr
             return Security::permissionFailure($this);
         }
 
-        increase_time_limit_to();
-        increase_memory_limit_to();
+        Environment::increaseTimeLimitTo();
+        Environment::increaseMemoryLimitTo();
 
         $response = "";
 
@@ -2026,7 +2027,7 @@ class CMSMain extends LeftAndMain implements CurrentPageIdentifier, PermissionPr
         if (!SecurityToken::inst()->checkRequest($request)) {
             return $this->httpError(400);
         }
-        increase_time_limit_to();
+        Environment::increaseTimeLimitTo();
         if (($id = $this->urlParams['ID']) && is_numeric($id)) {
             /** @var SiteTree $page */
             $page = SiteTree::get()->byID($id);

code/Model/ErrorPage.php

@@ -11,6 +11,7 @@ use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Control\HTTPResponse;
 use SilverStripe\Core\Config\Config;
 use SilverStripe\Core\Injector\Injector;
+use SilverStripe\Dev\Debug;
 use SilverStripe\Forms\DropdownField;
 use SilverStripe\Forms\FieldList;
 use SilverStripe\ORM\DB;

tests/model/SiteTreeTest.php

@@ -53,17 +53,6 @@ class SiteTreeTest extends SapphireTest
         SiteTreeTest_StageStatusInherit::class,
     );
 
-    /**
-     * Ensure any current member is logged out
-     */
-    public function logOut()
-    {
-        if ($member = Security::getCurrentUser()) {
-            Session::clear('loggedInAs');
-            Security::setCurrentUser(null);
-        }
-    }
-
     public function testCreateDefaultpages()
     {
             $remove = SiteTree::get();