drop hard dependency on the Stopwatch component

UPGRADE-3.4.md

@@ -16,6 +16,8 @@ Finder
 FrameworkBundle
 ---------------
 
+ * The `symfony/stopwatch` dependency has been removed, require it via `composer
+   require symfony/stopwatch` in your `dev` environment.
  * Using the `KERNEL_DIR` environment variable or the automatic guessing based
    on the `phpunit.xml` / `phpunit.xml.dist` file location is deprecated since 3.4. 
    Set the `KERNEL_CLASS` environment variable to the fully-qualified class name

src/Symfony/Bundle/FrameworkBundle/CHANGELOG.md

@@ -4,8 +4,10 @@ CHANGELOG
 3.4.0
 -----
 
-* Deprecated using the `KERNEL_DIR` environment variable with `KernelTestCase::getKernelClass()`.
-* Deprecated the `KernelTestCase::getPhpUnitXmlDir()` and `KernelTestCase::getPhpUnitCliConfigArgument()` methods.
+ * The `symfony/stopwatch` dependency has been removed, require it via `composer
+   require symfony/stopwatch` in your `dev` environment.
+ * Deprecated using the `KERNEL_DIR` environment variable with `KernelTestCase::getKernelClass()`.
+ * Deprecated the `KernelTestCase::getPhpUnitXmlDir()` and `KernelTestCase::getPhpUnitCliConfigArgument()` methods.
 
 3.3.0
 -----

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php

@@ -61,6 +61,7 @@ use Symfony\Component\Serializer\Normalizer\DateTimeNormalizer;
 use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
 use Symfony\Component\Serializer\Normalizer\JsonSerializableNormalizer;
 use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
+use Symfony\Component\Stopwatch\Stopwatch;
 use Symfony\Component\Validator\ConstraintValidatorInterface;
 use Symfony\Component\Validator\ObjectInitializerInterface;
 use Symfony\Component\WebLink\HttpHeaderSerializer;
@@ -639,9 +640,14 @@ class FrameworkExtension extends Extension
     {
         $loader->load('debug_prod.xml');
 
+        if (class_exists(Stopwatch::class)) {
+            $container->register('debug.stopwatch', Stopwatch::class);
+            $container->setAlias(Stopwatch::class, 'debug.stopwatch');
+        }
+
         $debug = $container->getParameter('kernel.debug');
 
-        if ($debug) {
+        if ($debug && class_exists(Stopwatch::class)) {
             $loader->load('debug.xml');
         }
 
@@ -881,7 +887,7 @@ class FrameworkExtension extends Extension
 
             $container->setParameter('templating.helper.form.resources', $config['form']['resources']);
 
-            if ($container->getParameter('kernel.debug')) {
+            if ($container->getParameter('kernel.debug') && class_exists(Stopwatch::class)) {
                 $loader->load('templating_debug.xml');
 
                 $container->setDefinition('templating.engine.php', $container->findDefinition('debug.templating.engine.php'));

src/Symfony/Bundle/FrameworkBundle/Resources/config/debug_prod.xml

@@ -23,9 +23,6 @@
             <argument>true</argument>
         </service>
 
-        <service id="debug.stopwatch" class="Symfony\Component\Stopwatch\Stopwatch" public="true" />
-        <service id="Symfony\Component\Stopwatch\Stopwatch" alias="debug.stopwatch" />
-
         <service id="debug.file_link_formatter" class="Symfony\Component\HttpKernel\Debug\FileLinkFormatter">
             <argument>%debug.file_link_format%</argument>
         </service>

src/Symfony/Bundle/FrameworkBundle/composer.json

@@ -29,7 +29,6 @@
         "symfony/filesystem": "~2.8|~3.0|~4.0",
         "symfony/finder": "~2.8|~3.0|~4.0",
         "symfony/routing": "~3.4|~4.0",
-        "symfony/stopwatch": "~2.8|~3.0|~4.0",
         "doctrine/cache": "~1.0"
     },
     "require-dev": {
@@ -47,6 +46,7 @@
         "symfony/security-core": "~3.2|~4.0",
         "symfony/security-csrf": "~2.8|~3.0|~4.0",
         "symfony/serializer": "~3.3|~4.0",
+        "symfony/stopwatch": "~2.8|~3.0|~4.0",
         "symfony/translation": "~3.2|~4.0",
         "symfony/templating": "~2.8|~3.0|~4.0",
         "symfony/validator": "~3.3|~4.0",