minor #18021 Don't use reflections when possible (Ener-Getick)

This PR was merged into the 2.3 branch.

Discussion
----------

Don't use reflections when possible

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

Use php functions instead of reflection when possible (to improve a bit the performance).

Commits
-------

a46270a Don't use reflections when possible

src/Symfony/Component/DependencyInjection/Container.php

@@ -363,9 +363,8 @@ class Container implements IntrospectableContainerInterface
     public function getServiceIds()
     {
         $ids = array();
-        $r = new \ReflectionClass($this);
-        foreach ($r->getMethods() as $method) {
-            if (preg_match('/^get(.+)Service$/', $method->name, $match)) {
+        foreach (get_class_methods($this) as $method) {
+            if (preg_match('/^get(.+)Service$/', $method, $match)) {
                 $ids[] = self::underscore($match[1]);
             }
         }

src/Symfony/Component/Serializer/Tests/Normalizer/GetSetMethodNormalizerTest.php

@@ -298,6 +298,11 @@ class GetSetDummy
     {
         throw new \RuntimeException('Dummy::otherMethod() should not be called');
     }
+
+    protected function getPrivate()
+    {
+        throw new \RuntimeException('Dummy::getPrivate() should not be called');        
+    }
 }
 
 class GetConstructorDummy

src/Symfony/Component/Validator/Mapping/PropertyMetadata.php

@@ -45,12 +45,11 @@ class PropertyMetadata extends MemberMetadata
      */
     protected function newReflectionMember($objectOrClassName)
     {
-        $class = new \ReflectionClass($objectOrClassName);
-        while (!$class->hasProperty($this->getName())) {
-            $class = $class->getParentClass();
+        while (!property_exists($objectOrClassName, $this->getName())) {
+            $objectOrClassName = get_parent_class($objectOrClassName);
         }
 
-        $member = new \ReflectionProperty($class->getName(), $this->getName());
+        $member = new \ReflectionProperty($objectOrClassName, $this->getName());
         $member->setAccessible(true);
 
         return $member;