Merge branch '2.7' into 2.8

* 2.7:
  Remove some unused variables, properties and methods
  [ExpressionLanguage] Fix parse error on 5.3
  [HttpKernel] remove noisy frame in controller stack traces
  [ExpressionLanguage] throw an SyntaxError instead of letting a undefined index notice
  Fix php doc in Table class
  bumped Symfony version to 2.7.40
  updated VERSION for 2.7.39
  update CONTRIBUTORS for 2.7.39
  updated CHANGELOG for 2.7.39

Author: nicolas-grekas

Context/LegacyExecutionContext.php

@@ -26,8 +26,6 @@
  */
 class LegacyExecutionContext extends ExecutionContext
 {
-    private $metadataFactory;
-
     /**
      * Creates a new context.
      *
@@ -44,7 +42,5 @@ public function __construct(ValidatorInterface $validator, $root, MetadataFactor
             $translator,
             $translationDomain
         );
-
-        $this->metadataFactory = $metadataFactory;
     }
 }