Merge branch '3.1'

* 3.1:
  [travis] Don't use parallel on HHVM
  [HttpKernel] Fix RequestDataCollector starting the session
  [appveyor] Ignore STATUS_HEAP_CORRUPTION errors on Windows
  [FrameworkBundle] Skip redis cache pools test on failed connection
  Fixed forwarded request data in templates
  [Security] Fix DebugAccessDecisionManager when object is not a scalar
  Skip some tests on HHVM due to a PHPunit bug
  Use the Trusty Travis infrastructure for HHVM builds
  LdapUserProvider: add missing argument type doc
  Fixed issue with missing argument in the abstract service definition for the ldap user provider
  Add 3.1 to  PR template branch row, remove 2.3
  Improve memory efficiency
  [Console] Fix BC break introduced by #18101
  document method name changes in Voter class
  add missing hint for vote() argument type
  [#18838] add a test to avoid regressions
  bumped Symfony version to 3.1.1
  updated VERSION for 3.1.0
  updated CHANGELOG for 3.1.0

Conflicts:
	src/Symfony/Component/HttpKernel/Kernel.php

Author: nicolas-grekas

Resources/views/Collector/request.html.twig

@@ -13,7 +13,7 @@
         {% endset %}
     {% endif %}
 
-    {% if collector.forward %}
+    {% if collector.forward|default(false) %}
         {% set forward_handler %}
             {% import _self as helper %}
             {{ helper.set_handler(collector.forward.controller) }}
@@ -26,7 +26,7 @@
         <span class="sf-toolbar-status sf-toolbar-status-{{ request_status_code_color }}">{{ collector.statuscode }}</span>
         {% if collector.route %}
             {% if collector.redirect %}{{ include('@WebProfiler/Icon/redirect.svg') }}{% endif %}
-            {% if collector.forward %}{{ include('@WebProfiler/Icon/forward.svg') }}{% endif %}
+            {% if collector.forward|default(false) %}{{ include('@WebProfiler/Icon/forward.svg') }}{% endif %}
             <span class="sf-toolbar-label">{{ 'GET' != collector.method ? collector.method }} @</span>
             <span class="sf-toolbar-value sf-toolbar-info-piece-additional">{{ collector.route }}</span>
         {% endif %}

Resources/views/Profiler/layout.html.twig

@@ -44,7 +44,7 @@
                             </dl>
                         {%- endif %}
 
-                        {% if request_collector and request_collector.forward and request_collector.forward.controller.class is defined -%}
+                        {% if request_collector and request_collector.forward|default(false) and request_collector.forward.controller.class is defined -%}
                             {%- set forward = request_collector.forward -%}
                             {%- set controller = forward.controller -%}
                             <dl class="metadata">