Merge branch '3.1'

* 3.1:
  [VarDumper] Various minor fixes & cleanups
  Revert "bug #18935 [Form] Consider a violation even if the form is not submitted (egeloen)"
  [Config] Fix DirectoryResourceTest for symlinks
  [HttpKernel] Add missing SsiFragmentRendererTest
  [DoctrineBridge] Fix exception message and tests after misresolved merge
  Fixes the calendar in constructor to handle null

Author: nicolas-grekas

Tests/Resource/DirectoryResourceTest.php

@@ -53,7 +53,7 @@ protected function removeDirectory($directory)
     public function testGetResource()
     {
         $resource = new DirectoryResource($this->directory);
-        $this->assertSame($this->directory, $resource->getResource(), '->getResource() returns the path to the resource');
+        $this->assertSame(realpath($this->directory), $resource->getResource(), '->getResource() returns the path to the resource');
     }
 
     public function testGetPattern()
@@ -166,7 +166,7 @@ public function testSerializeUnserialize()
 
         $unserialized = unserialize(serialize($resource));
 
-        $this->assertSame($this->directory, $resource->getResource());
+        $this->assertSame(realpath($this->directory), $resource->getResource());
         $this->assertSame('/\.(foo|xml)$/', $resource->getPattern());
     }