minor #15383 [Security] Small optimization in AccessDecisionManager (jderusse)

This PR was merged into the 2.8 branch.

Discussion
----------

[Security] Small optimization in AccessDecisionManager

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | na
| License       | MIT
| Doc PR        | na

- Remove unused variable `$abstain`
- Remove equals comparison: if not `$grant > $deny` and not `$deny > $grant` then `$grant` equals `$deny`

Commits
-------

0e93463 Small optimization in AccessDecisionManager

src/Symfony/Component/Security/Core/Authorization/AccessDecisionManager.php

@@ -150,7 +150,6 @@ class AccessDecisionManager implements AccessDecisionManagerInterface
     {
         $grant = 0;
         $deny = 0;
-        $abstain = 0;
         foreach ($this->voters as $voter) {
             $result = $voter->vote($token, $object, $attributes);
 
@@ -163,11 +162,6 @@ class AccessDecisionManager implements AccessDecisionManagerInterface
                 case VoterInterface::ACCESS_DENIED:
                     ++$deny;
 
-                    break;
-
-                default:
-                    ++$abstain;
-
                     break;
             }
         }
@@ -180,7 +174,7 @@ class AccessDecisionManager implements AccessDecisionManagerInterface
             return false;
         }
 
-        if ($grant == $deny && $grant != 0) {
+        if ($grant > 0) {
             return $this->allowIfEqualGrantedDeniedDecisions;
         }