Update src/Symfony/Component/HttpFoundation/Request.php

This makes `getContentType()` work when a regular form is submitted.
[Form] Choice children can be template customized like collection
[Serializer] Added PropertyNormalizer, a new normalizer that maps an object's properties to an array
Call AuthenticationManager in AnonymousAuthenticationListener
[HttpKernel] Extract method to make callable controller in ControllerResolver

correct naming
[MonologBridge] Ignore empty context/extra by default in the ConsoleFormatter
[WebProfilerBundle] turbolinks compatibility
[Security] made it possible to override the default success/failure handler
Response::isNotModified returns true when If-Modified-Since is later than Last-Modified
bug #11079 Response::isNotModified returns true when If-Modified-Since is later than Last-Modified (skolodyazhnyy)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #11079).

Discussion
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Response::isNotModified returns true when If-Modified-Since is later than Last-Modified

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10501,  #10857
| License       | MIT
| Doc PR        |

Patch for #10501. I have reworked a bit `Response::isNotModified` method to make it more readable. Now it's comparing If-Modified-Since and Last-Modified as dates.

Commits
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42ec76e Response::isNotModified returns true when If-Modified-Since is later than Last-Modified
[Form] Add a form error if post_max_size has been reached.
minor #11504 [WebProfilerBundle] turbolinks compatibility (DraCzris)

This PR was merged into the 2.3 branch.

Discussion
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[WebProfilerBundle] turbolinks compatibility

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Fix profiler when using turbolinks. (Without this, profiler is rendered without assets)

Commits
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c65b4c7 [WebProfilerBundle] turbolinks compatibility
[Form] Moved POST_MAX_SIZE validation from FormValidator to request handler
added the possibility to return null from SimplePreAuthenticationListener
[Validator] Added "payload" option to all constraints for attaching domain-specific data
[WebProfilerBundle] Show AJAX requests in the symfony profiler toolbar
[WebProfilerBundle] improved the ajax section of the WDT
removed uneeded web_profiler.debug_toolbar.excluded_ajax_paths parameter in the container
removed hack
fixed bug