Merge branch '2.7' into 2.8

* 2.7:
  [VarDumper] Fix tests on PHP 7
  [DomCrawler] Clarify the value returned by getPhpFiles()
  [DependencyInjection] Fix #16461 Let Container::set() replace existing aliases
  avoid (string) catchable fatal error for instances of __PHP_Incomplete_Class
  remove unnecessary retrieval and setting of data
  avoid (string) catchable fatal error for __PHP_Incomplete_Class instances
  sendContent return as parent.
  [FrameworkBundle] Fix a typo
  Added more exceptions to singularify method

Author: nicolas-grekas

Command/TranslationUpdateCommand.php

@@ -47,8 +47,9 @@ protected function configure()
             ))
             ->setDescription('Updates the translation file')
             ->setHelp(<<<'EOF'
-The <info>%command.name%</info> command extract translation strings from templates
+The <info>%command.name%</info> command extracts translation strings from templates
 of a given bundle or the app folder. It can display them or merge the new ones into the translation files.
+
 When new translation strings are found it can automatically add a prefix to the translation
 message.