Merge branch '2.8' into 3.3

* 2.8:
  fix merge
  Fix 7.2 compat layer
  Fix PHP 7.2 support
  [HttpFoundation] Add missing session.lazy_write config option
  [HttpFoundation] Combine Cache-Control headers
  [Form] fix parsing invalid floating point numbers
  Escape command usage when displaying it in the text descriptor
  Use for=ID on radio/checkbox label.

Author: nicolas-grekas

Tests/Command/CacheClearCommand/CacheClearCommandTest.php

@@ -67,7 +67,7 @@ public function testCacheIsFreshAfterCacheClearedWithWarmup()
         $finder = new Finder();
         $metaFiles = $finder->files()->in($this->kernel->getCacheDir())->name('*.php.meta');
         // simply check that cache is warmed up
-        $this->assertGreaterThanOrEqual(1, count($metaFiles));
+        $this->assertNotEmpty($metaFiles);
         $configCacheFactory = new ConfigCacheFactory(true);
 
         foreach ($metaFiles as $file) {

Tests/Controller/ControllerTraitTest.php

@@ -373,6 +373,9 @@ public function testRedirectToRoute()
         $this->assertSame(302, $response->getStatusCode());
     }
 
+    /**
+     * @runInSeparateProcess
+     */
     public function testAddFlash()
     {
         $flashBag = new FlashBag();

composer.json

@@ -23,7 +23,7 @@
         "symfony/dependency-injection": "~3.3",
         "symfony/config": "~3.3",
         "symfony/event-dispatcher": "^3.3.1",
-        "symfony/http-foundation": "~3.3",
+        "symfony/http-foundation": "^3.3.11",
         "symfony/http-kernel": "~3.3",
         "symfony/polyfill-mbstring": "~1.0",
         "symfony/filesystem": "~2.8|~3.0",