This PR was merged into the 3.4 branch.Discussion----------[EventDispatcher] Revers event tracing order| Q             | A| ------------- | ---| Branch?       | 3.4| Bug fix?      | yes| New feature?  | no| BC breaks?    | no     <!-- seehttps://symfony.com/bc -->| Deprecations? | no| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->| License       | MIT| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->Split from#29312 for 3.4This traces events in dispatch order.Before:![image](https://user-images.githubusercontent.com/1047696/49330956-5f71e780-f596-11e8-8701-80458e715213.png)After:![image](https://user-images.githubusercontent.com/1047696/49330963-79abc580-f596-11e8-8666-5535afd59b31.png)Here we see it also collects "terminate" events (both kernel & console for not-called listeners). In case of exception page the fix is even better:#29312 (review)Which now correctly shows the kernel.exception event of the main request is dispatched _before_ the kernel.request event of the sub-request.Moreover, it de-duplicates events. So we actually see the sub-request events 🎉_Havent looked at tests yet._Commits-------2570d6f [EventDispatcher] Revers event tracing order

…eset() callStack to null (mlievertz)This PR was merged into the 3.4 branch.Discussion----------[Event Dispatcher] fixed 29703: TraceableEventDispatcher reset() callStack to null[Event Dispatcher] fixed 29703: TraceableEventDispatcher reset now sets callStack to null with test to dispatch after reset.| Q             | A| ------------- | ---| Branch?       | 3.4 <!-- see below -->| Bug fix?      | yes| New feature?  | no <!-- don't forget to update src/**/CHANGELOG.md files -->| BC breaks?    | no     <!-- seehttps://symfony.com/bc -->| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->| Fixed tickets |#29703    <!-- #-prefixed issue number(s), if any -->| License       | MIT| Doc PR        | N/A <!-- required for new features -->[Event Dispatcher] fixed 29703: TraceableEventDispatcher reset now sets callStack to null with test to dispatch after reset. Basically#29411 introduced an issue where calling dispatch after a reset would throw an error because now reset set callStack to array but dispatch expected either SplObjectStorage or null. Now reset sets null. Also added a test to verify dispatch works following a call to reset.Commits-------51bcdb8 [Event Dispatcher] fixed 29703: TraceableEventDispatcher reset now sets callStack to null with test to dispatch after reset.

This PR was merged into the 3.4 branch.Discussion----------[EventDispatcher] Fix unknown priority| Q             | A| ------------- | ---| Branch?       | 3.4| Bug fix?      | yes| New feature?  | no| BC breaks?    | no     <!-- seehttps://symfony.com/bc -->| Deprecations? | no| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->| License       | MIT| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->Somehow, after#29411 the profiler actually shows the security firewall `ContextListener`.This listener removes itself at call time, but at this point it's wrapped reference is already in the call stack; to be displayed in the profiler.Because the wrapped listener lazily collects its priority - it asks it from the dispatcher -  we get null; the listener was already removed.This causes the profiler to render `-` by default:![image](https://user-images.githubusercontent.com/1047696/50850320-d5c5ee80-1379-11e9-8516-0c6bc54512ce.png)This fixes it by always passing the expected priority at call time.Commits-------9fb619a [EventDispatcher] Fix unknown priority

This PR was merged into the 3.4 branch.Discussion----------[EventDispatcher] cleanup| Q             | A| ------------- | ---| Branch?       | 3.4| Bug fix?      | yes| New feature?  | no| BC breaks?    | no     <!-- seehttps://symfony.com/bc -->| Deprecations? | no| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->| License       | MIT| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->forgotten in#29411 (https://github.com/symfony/symfony/pull/29411/files#diff-a72bc1daccda0ec7bfcfae0e8d3df141L287)Commits-------19134c0 [EventDispatcher] cleanup