Merge branch '3.4' into 4.4

* 3.4:
  [Validator] fix tests
  ensure that the validator is a mock object for backwards-compatibility

Test/ConstraintValidatorTestCase.php

@@ -117,7 +117,7 @@ protected function createContext()
         $validator->expects($this->any())
             ->method('inContext')
             ->with($context)
-            ->willReturn(new AssertingContextualValidator());
+            ->willReturn($this->getMockBuilder(AssertingContextualValidator::class)->setMethods(null)->getMock());
 
         return $context;
     }