Merge branch '3.4' into 4.1

* 3.4:
  [VarDumper] fix dump of closures created from callables
  [DI] fix dumping inlined services
  Add framework asset changes to upgrade 3.0 guide
  [Travis] Bump ext-mongodb to 1.5.2 on Travis
  [DI] dont track classes/interfaces used to compute autowiring error messages
  [DI] fix GraphvizDumper ignoring inline definitions
  bumped Symfony version to 3.4.19
  updated VERSION for 3.4.18
  updated CHANGELOG for 3.4.18
  bumped Symfony version to 2.8.48
  updated VERSION for 2.8.47
  update CONTRIBUTORS for 2.8.47
  updated CHANGELOG for 2.8.47
  Fix ini_get() for boolean values

Author: nicolas-grekas

.travis.yml

@@ -160,7 +160,7 @@ before_install:
           fi
 
           tfold ext.apcu tpecl apcu-5.1.6 apcu.so $INI
-          tfold ext.mongodb tpecl mongodb-1.5.0 mongodb.so $INI
+          tfold ext.mongodb tpecl mongodb-1.5.2 mongodb.so $INI
           tfold ext.amqp tpecl amqp-1.9.3 amqp.so $INI
       done
 
@@ -223,7 +223,7 @@ install:
               break
           fi
           phpenv global $PHP
-          ([[ $deps ]] && cd src/Symfony/Component/HttpFoundation; composer require --dev --no-update mongodb/mongodb)
+          ([[ $deps ]] && cd src/Symfony/Component/HttpFoundation; composer config platform.ext-mongodb 1.5.2; composer require --dev --no-update mongodb/mongodb)
           tfold 'composer update' $COMPOSER_UP
           tfold 'phpunit install' ./phpunit install
           if [[ $deps = high ]]; then