Merge branch '2.8' into 3.1

* 2.8:
  [travis/appveyor] Wire simple-phpunit
  [Console] fixed PHP7 Errors are now handled and converted to Exceptions
  Fix #19721
  Fix translation:update command count
  bumped Symfony version to 2.8.12
  updated VERSION for 2.8.11
  updated CHANGELOG for 2.8.11
  bumped Symfony version to 2.7.19
  updated VERSION for 2.7.18
  update CONTRIBUTORS for 2.7.18
  updated CHANGELOG for 2.7.18
  [Security] Optimize RoleHierarchy's buildRoleMap method

Author: fabpot

Core/Role/RoleHierarchy.php

@@ -65,9 +65,17 @@ protected function buildRoleMap()
                 }
 
                 $visited[] = $role;
-                $this->map[$main] = array_unique(array_merge($this->map[$main], $this->hierarchy[$role]));
-                $additionalRoles = array_merge($additionalRoles, array_diff($this->hierarchy[$role], $visited));
+
+                foreach ($this->hierarchy[$role] as $roleToAdd) {
+                    $this->map[$main][] = $roleToAdd;
+                }
+
+                foreach (array_diff($this->hierarchy[$role], $visited) as $additionalRole) {
+                    $additionalRoles[] = $additionalRole;
+                }
             }
+
+            $this->map[$main] = array_unique($this->map[$main]);
         }
     }
 }