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

Parser/TokenStream.php

@@ -31,11 +31,6 @@ class TokenStream
      */
     private $tokens = array();
 
-    /**
-     * @var bool
-     */
-    private $frozen = false;
-
     /**
      * @var Token[]
      */
@@ -49,7 +44,7 @@ class TokenStream
     /**
      * @var Token|null
      */
-    private $peeked = null;
+    private $peeked;
 
     /**
      * @var bool
@@ -75,8 +70,6 @@ public function push(Token $token)
      */
     public function freeze()
     {
-        $this->frozen = true;
-
         return $this;
     }