Merge branch '2.8' into 3.1

* 2.8:
  [FrameworkBundle] Check for class existence before is_subclass_of
  Update GroupSequence.php
  Code enhancement and cleanup
  [Form] Fix transformer tests after the ICU update
  [DI] Add anti-regression test
  Revert "minor #19689 [DI] Cleanup array_key_exists (ro0NL)"
  bumped Symfony version to 2.8.11
  updated VERSION for 2.8.10
  updated CHANGELOG for 2.8.10
  [BrowserKit] Fix cookie expiration on 32 bit systems
  bumped Symfony version to 2.7.18
  updated VERSION for 2.7.17
  update CONTRIBUTORS for 2.7.17
  updated CHANGELOG for 2.7.17
  Update misleading comment about RFC4627

ErrorHandler.php

@@ -348,10 +348,12 @@ class ErrorHandler
     /**
      * Handles errors by filtering then logging them according to the configured bit fields.
      *
-     * @param int    $type    One of the E_* constants
+     * @param int    $type      One of the E_* constants
+     * @param string $message
      * @param string $file
      * @param int    $line
      * @param array  $context
+     * @param array  $backtrace
      *
      * @return bool Returns false when no handling happens so that the PHP engine can handle the error itself
      *

Exception/FlattenException.php

@@ -222,7 +222,10 @@ class FlattenException
             if (++$count > 1e4) {
                 return array('array', '*SKIPPED over 10000 entries*');
             }
-            if (is_object($value)) {
+            if ($value instanceof \__PHP_Incomplete_Class) {
+                // is_object() returns false on PHP<=7.1
+                $result[$key] = array('incomplete-object', $this->getClassNameFromIncomplete($value));
+            } elseif (is_object($value)) {
                 $result[$key] = array('object', get_class($value));
             } elseif (is_array($value)) {
                 if ($level > 10) {
@@ -236,9 +239,6 @@ class FlattenException
                 $result[$key] = array('boolean', $value);
             } elseif (is_resource($value)) {
                 $result[$key] = array('resource', get_resource_type($value));
-            } elseif ($value instanceof \__PHP_Incomplete_Class) {
-                // Special case of object, is_object will return false
-                $result[$key] = array('incomplete-object', $this->getClassNameFromIncomplete($value));
             } else {
                 $result[$key] = array('string', (string) $value);
             }

ExceptionHandler.php

@@ -299,6 +299,7 @@ EOF;
                 border-bottom:1px solid #ccc;
                 border-right:1px solid #ccc;
                 border-left:1px solid #ccc;
+                word-wrap: break-word;
             }
             .sf-reset .block_exception { background-color:#ddd; color: #333; padding:20px;
                 -webkit-border-top-left-radius: 16px;

Tests/DebugClassLoaderTest.php

@@ -13,7 +13,6 @@ namespace Symfony\Component\Debug\Tests;
 
 use Symfony\Component\Debug\DebugClassLoader;
 use Symfony\Component\Debug\ErrorHandler;
-use Symfony\Component\Debug\Exception\ContextErrorException;
 
 class DebugClassLoaderTest extends \PHPUnit_Framework_TestCase
 {

Tests/MockExceptionHandler.php

@@ -13,7 +13,7 @@ namespace Symfony\Component\Debug\Tests;
 
 use Symfony\Component\Debug\ExceptionHandler;
 
-class MockExceptionHandler extends Exceptionhandler
+class MockExceptionHandler extends ExceptionHandler
 {
     public $e;