Remove function_exists(__phpunit_run_isolated_test) checks

This PR was squashed before being merged into the 2.7 branch (closes #24342).

Discussion
----------

removed useless PHPDoc

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | no
| New feature?  | no <!-- don't forget updating src/**/CHANGELOG.md files -->
| BC breaks?    | no
| Deprecations? | no <!-- don't forget updating UPGRADE-*.md files -->
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        | n/a

Commits
-------

5ee9043d8b removed useless PHPDoc

DebugClassLoader.php

@@ -34,8 +34,6 @@ class DebugClassLoader
     private static $darwinCache = array('/' => array('/', array()));
 
     /**
-     * Constructor.
-     *
      * @param callable|object $classLoader Passing an object is @deprecated since version 2.5 and support for it will be removed in 3.0
      */
     public function __construct($classLoader)
@@ -205,18 +203,11 @@ class DebugClassLoader
             } elseif (preg_match('#\n \* @deprecated (.*?)\r?\n \*(?: @|/$)#s', $refl->getDocComment(), $notice)) {
                 self::$deprecated[$name] = preg_replace('#\s*\r?\n \* +#', ' ', $notice[1]);
             } else {
-                if (2 > $len = 1 + (strpos($name, '\\', 1 + strpos($name, '\\')) ?: strpos($name, '_'))) {
+                if (2 > $len = 1 + (strpos($name, '\\') ?: strpos($name, '_'))) {
                     $len = 0;
                     $ns = '';
                 } else {
-                    switch ($ns = substr($name, 0, $len)) {
-                        case 'Symfony\Bridge\\':
-                        case 'Symfony\Bundle\\':
-                        case 'Symfony\Component\\':
-                            $ns = 'Symfony\\';
-                            $len = strlen($ns);
-                            break;
-                    }
+                    $ns = substr($name, 0, $len);
                 }
                 $parent = get_parent_class($class);
 

ExceptionHandler.php

@@ -151,8 +151,6 @@ class ExceptionHandler
      * If you have the Symfony HttpFoundation component installed,
      * this method will use it to create and send the response. If not,
      * it will fallback to plain PHP functions.
-     *
-     * @param \Exception $exception An \Exception instance
      */
     private function failSafeHandle(\Exception $exception)
     {
@@ -215,8 +213,6 @@ class ExceptionHandler
     /**
      * Gets the HTML content associated with the given exception.
      *
-     * @param FlattenException $exception A FlattenException instance
-     *
      * @return string The content as a string
      */
     public function getContent(FlattenException $exception)
@@ -283,8 +279,6 @@ EOF;
     /**
      * Gets the stylesheet associated with the given exception.
      *
-     * @param FlattenException $exception A FlattenException instance
-     *
      * @return string The stylesheet as a string
      */
     public function getStylesheet(FlattenException $exception)

Tests/DebugClassLoaderTest.php

@@ -208,7 +208,7 @@ class DebugClassLoaderTest extends TestCase
 
         $xError = array(
             'type' => E_USER_DEPRECATED,
-            'message' => 'The Test\Symfony\Component\Debug\Tests\\'.$class.' class '.$type.' Symfony\Component\Debug\Tests\Fixtures\\'.$super.' that is deprecated but this is a test deprecation notice.',
+            'message' => 'The Test\Symfony\Component\Debug\Tests\\'.$class.' class '.$type.' Symfony\Component\Debug\Tests\Fixtures\\'.$super.' that is deprecated but this is a test deprecation notice',
         );
 
         $this->assertSame($xError, $lastError);

Tests/ErrorHandlerTest.php

@@ -79,7 +79,9 @@ class ErrorHandlerTest extends TestCase
             $this->assertEquals(E_NOTICE, $exception->getSeverity());
             $this->assertEquals(__FILE__, $exception->getFile());
             $this->assertRegExp('/^Notice: Undefined variable: (foo|bar)/', $exception->getMessage());
-            $this->assertArrayHasKey('foobar', $exception->getContext());
+            if (\PHP_VERSION_ID < 70200) {
+                $this->assertArrayHasKey('foobar', $exception->getContext());
+            }
 
             $trace = $exception->getTrace();
             $this->assertEquals(__FILE__, $trace[0]['file']);

Tests/Fixtures/DeprecatedClass.php

@@ -4,7 +4,7 @@ namespace Symfony\Component\Debug\Tests\Fixtures;
 
 /**
  * @deprecated but this is a test
- *             deprecation notice.
+ *             deprecation notice
  * @foobar
  */
 class DeprecatedClass

Tests/Fixtures/DeprecatedInterface.php

@@ -4,7 +4,7 @@ namespace Symfony\Component\Debug\Tests\Fixtures;
 
 /**
  * @deprecated but this is a test
- *             deprecation notice.
+ *             deprecation notice
  * @foobar
  */
 interface DeprecatedInterface