bug symfony#21257 [Profiler][Form] Fix form profiler errors profiler_dump (ogizanagi)

This PR was merged into the 3.2 branch.

Discussion
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[Profiler][Form] Fix form profiler errors profiler_dump

| Q             | A
| ------------- | ---
| Branch?       | 3.2
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | N/A
| License       | MIT
| Doc PR        | N/A

|Before|After|
|-|-|
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<img width="807" alt="screenshot 2017-01-12 a 20 12 59" src="https://cloud.githubusercontent.com/assets/2211145/21904499/323d1a38-d904-11e6-85ef-0957ef226278.PNG">|<img width="806" alt="screenshot 2017-01-12 a 20 13 38" src="https://cloud.githubusercontent.com/assets/2211145/21904500/32429710-d904-11e6-9bed-0d8e37262cd5.PNG">|

Commits
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207fab6 [Profiler][Form] Fix form profiler errors profiler_dump

Author: nicolas-grekas

src/Symfony/Bundle/WebProfilerBundle/Resources/views/Collector/form.html.twig

@@ -492,7 +492,9 @@
                     <td>
                         {% if error.trace %}
                             <span class="newline">Caused by:</span>
-                            {{ profiler_dump(error.trace, maxDepth=2) }}
+                            {% for stacked in error.trace %}
+                                {{ profiler_dump(stacked) }}
+                            {% endfor %}
                         {% else %}
                             <em>Unknown.</em>
                         {% endif %}