Merge branch '2.7' into 2.8

* 2.7:
  fixed test
  [Request] Ignore invalid IP addresses sent by proxies
  Throw for missing container extensions
  [TwigBridge] add missing unit tests (AppVariable)
  Able to load big xml files with DomCrawler
  fixed typo
  [Form] Fix constraints could be null if not set
  [Finder] Check PHP version before applying a workaround for a PHP bug
  fixed CS
  add defaultNull to version
  sort bundles in config:dump-reference command
  Fixer findings.
  [Translation][Writer] avoid calling setBackup if the dumper is not an instance of FileDumper.
  [FrameworkBundle] Compute the kernel root hash only one time

Author: fabpot

Tests/Node/AbstractNodeTest.php

@@ -28,5 +28,6 @@ public function testSpecificityValue(NodeInterface $node, $value)
     }
 
     abstract public function getToStringConversionTestData();
+
     abstract public function getSpecificityValueTestData();
 }

Tests/Parser/Handler/AbstractHandlerTest.php

@@ -43,7 +43,9 @@ public function testDontHandleValue($value)
     }
 
     abstract public function getHandleValueTestData();
+
     abstract public function getDontHandleValueTestData();
+
     abstract protected function generateHandler();
 
     protected function assertStreamEmpty(TokenStream $stream)