skip tests requiring the intl extension if it's not installed

Author: xabbuh

src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/NumberToLocalizedStringTransformerTest.php

@@ -638,6 +638,8 @@ public function testReverseTransformSmallInt()
      */
     public function testReverseTransformENotation($output, $input)
     {
+        IntlTestHelper::requireFullIntl($this);
+
         \Locale::setDefault('en');
 
         $transformer = new NumberToLocalizedStringTransformer();