Merge branch '3.4' into 4.1

* 3.4:
  fix compatibility with Twig >= 2.6.1
  [Form] SA fix
  fix compatibility with PHPUnit 4.8
  remove return type hint for PHP 5 compatibility
  Component CssSelector tests
  [DebugClassLoader] Readd findFile() method
  [Console] Fix composer.json suggest/provide
  Revert "bug #29597 [DI] fix reporting bindings on overriden services as unused (nicolas-grekas)"
  Fixed exception wording
  Fix SwiftMailerHandler to support Monolog's latest reset functionality

Author: xabbuh

Test/Traits/ValidatorExtensionTrait.php

@@ -18,8 +18,14 @@
 
 trait ValidatorExtensionTrait
 {
+    /**
+     * @var ValidatorInterface|null
+     */
     protected $validator;
 
+    /**
+     * @return ValidatorExtension
+     */
     protected function getValidatorExtension()
     {
         if (!interface_exists(ValidatorInterface::class)) {
@@ -31,9 +37,9 @@ protected function getValidatorExtension()
         }
 
         $this->validator = $this->getMockBuilder(ValidatorInterface::class)->getMock();
-        $metadata = $this->getMockBuilder(ClassMetadata::class)->disableOriginalConstructor()->setMethods(array('addPropertyConstraint'))->getMock();
+        $metadata = $this->getMockBuilder(ClassMetadata::class)->disableOriginalConstructor()->setMethods(['addPropertyConstraint'])->getMock();
         $this->validator->expects($this->any())->method('getMetadataFor')->will($this->returnValue($metadata));
-        $this->validator->expects($this->any())->method('validate')->will($this->returnValue(array()));
+        $this->validator->expects($this->any())->method('validate')->will($this->returnValue([]));
 
         return new ValidatorExtension($this->validator);
     }