Squiz/ClosingDeclarationComment: remove unreachable condition

This commit removes an if condition that cannot be true. The
`$closingBracket` variable can never be null as the sniff already bows
out before setting the variable when checking if
`isset($tokens[$stackPtr]['scope_closer']) === false`.

Author: rodrigoprimo

src/Standards/Squiz/Sniffs/Commenting/ClosingDeclarationCommentSniff.php

@@ -85,11 +85,6 @@ public function process(File $phpcsFile, $stackPtr)
 
         $closingBracket = $tokens[$stackPtr]['scope_closer'];
 
-        if ($closingBracket === null) {
-            // Possible inline structure. Other tests will handle it.
-            return;
-        }
-
         $data = [$comment];
         if (isset($tokens[($closingBracket + 1)]) === false || $tokens[($closingBracket + 1)]['code'] !== T_COMMENT) {
             $next = $phpcsFile->findNext(T_WHITESPACE, ($closingBracket + 1), null, true);