Remove obsolete slash

`WCF_DIR` already includes a trailing slash
ref https://www.woltlab.com/community/thread/311621-doppelte-im-code/

Author: BurntimeX

wcfsetup/install/files/lib/data/reaction/type/ReactionTypeAction.class.php

@@ -87,8 +87,8 @@ public function create()
             if (!$iconFile->isProcessed()) {
                 $fileName = $reactionType->reactionTypeID . '-' . $iconFile->getFilename();
 
-                \rename($iconFile->getLocation(), WCF_DIR . '/images/reaction/' . $fileName);
-                $iconFile->setProcessed(WCF_DIR . '/images/reaction/' . $fileName);
+                \rename($iconFile->getLocation(), WCF_DIR . 'images/reaction/' . $fileName);
+                $iconFile->setProcessed(WCF_DIR . 'images/reaction/' . $fileName);
 
                 $updateData['iconFile'] = $fileName;
             }
@@ -142,8 +142,8 @@ public function update()
                 if (!$iconFile->isProcessed()) {
                     $fileName = $object->reactionTypeID . '-' . $iconFile->getFilename();
 
-                    \rename($iconFile->getLocation(), WCF_DIR . '/images/reaction/' . $fileName);
-                    $iconFile->setProcessed(WCF_DIR . '/images/reaction/' . $fileName);
+                    \rename($iconFile->getLocation(), WCF_DIR . 'images/reaction/' . $fileName);
+                    $iconFile->setProcessed(WCF_DIR . 'images/reaction/' . $fileName);
 
                     $updateData['iconFile'] = $fileName;
                 }
@@ -193,8 +193,8 @@ public function delete()
             ]);
 
             // Delete outdated reaction type icon.
-            if (isset($object->iconFile) && \file_exists(WCF_DIR . '/images/reaction/' . $object->iconFile)) {
-                @\unlink(WCF_DIR . '/images/reaction/' . $object->iconFile);
+            if (isset($object->iconFile) && \file_exists(WCF_DIR . 'images/reaction/' . $object->iconFile)) {
+                @\unlink(WCF_DIR . 'images/reaction/' . $object->iconFile);
             }
         }
 

wcfsetup/install/files/lib/system/WCF.class.php

@@ -180,7 +180,7 @@ class WCF
      */
     protected static $zendOpcacheEnabled;
 
-    public const BOOTSTRAP_LOADER = \WCF_DIR . '/lib/bootstrap.php';
+    public const BOOTSTRAP_LOADER = \WCF_DIR . 'lib/bootstrap.php';
 
     /**
      * Calls all init functions of the WCF class.

wcfsetup/install/files/lib/system/bbcode/BBCodeHandler.class.php

@@ -164,7 +164,7 @@ public function getHighlighterMeta()
             $this->highlighterMeta = JSON::decode(\preg_replace(
                 '/.*\/\*!START\*\/\s*const\s*metadata\s*=\s*(.*)\s*;\s*\/\*!END\*\/.*/s',
                 '\\1',
-                \file_get_contents(WCF_DIR . '/js/WoltLabSuite/Core/prism-meta.js')
+                \file_get_contents(WCF_DIR . 'js/WoltLabSuite/Core/prism-meta.js')
             ));
         }