[FrameworkBundle] made the Request service synchronized

This change allows any service to depend on the Request (via a method
call) and always have the right Request instance without the need for
the service to be in the request scope (you still need to set the
Request reference as non-strict).

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

@@ -40,7 +40,7 @@
             This service definition only defines the scope of the request.
             It is used to check references scope.
         -->
-        <service id="request" scope="request" synthetic="true" />
+        <service id="request" scope="request" synthetic="true" synchronized="true" />
 
         <service id="service_container" synthetic="true" />