Generic/UselessOverridingMethod: remove $next === false checks

Early on in the sniff code, it is checked if the method has a scope
opener (which is never true if there is no scope closer). So there
always will be at least one token after the scope opener, the scope
closer.

This means that `$next === false` checks are not necessary. `$next` will
never be false.

To be extra careful, a check to confirm that the scope closer is present
was added to the beginning of the sniff.

src/Standards/Generic/Sniffs/CodeAnalysis/UselessOverridingMethodSniff.php

@@ -56,7 +56,7 @@ public function process(File $phpcsFile, $stackPtr)
         $token  = $tokens[$stackPtr];
 
         // Skip function without body.
-        if (isset($token['scope_opener']) === false) {
+        if (isset($token['scope_opener'], $token['scope_closer']) === false) {
             return;
         }
 
@@ -93,23 +93,23 @@ public function process(File $phpcsFile, $stackPtr)
         $next = $phpcsFile->findNext(Tokens::$emptyTokens, ($next + 1), null, true);
 
         // Skip for invalid code.
-        if ($next === false || $tokens[$next]['code'] !== T_DOUBLE_COLON) {
+        if ($tokens[$next]['code'] !== T_DOUBLE_COLON) {
             return;
         }
 
         // Find next non empty token index, should be the name of the method being called.
         $next = $phpcsFile->findNext(Tokens::$emptyTokens, ($next + 1), null, true);
 
         // Skip for invalid code or other method.
-        if ($next === false || strcasecmp($tokens[$next]['content'], $methodName) !== 0) {
+        if (strcasecmp($tokens[$next]['content'], $methodName) !== 0) {
             return;
         }
 
         // Find next non empty token index, should be the open parenthesis.
         $next = $phpcsFile->findNext(Tokens::$emptyTokens, ($next + 1), null, true);
 
         // Skip for invalid code.
-        if ($next === false || $tokens[$next]['code'] !== T_OPEN_PARENTHESIS || isset($tokens[$next]['parenthesis_closer']) === false) {
+        if ($tokens[$next]['code'] !== T_OPEN_PARENTHESIS || isset($tokens[$next]['parenthesis_closer']) === false) {
             return;
         }
 
@@ -134,7 +134,7 @@ public function process(File $phpcsFile, $stackPtr)
         }//end for
 
         $next = $phpcsFile->findNext(Tokens::$emptyTokens, ($next + 1), null, true);
-        if ($next === false || $tokens[$next]['code'] !== T_SEMICOLON) {
+        if ($tokens[$next]['code'] !== T_SEMICOLON) {
             return;
         }