Laravel 5.6 updates

Travis config update

Removed HHVM script as Laravel no longer support HHVM after releasing 5.3

vendor/symfony/var-dumper/Tests/Caster/GmpCasterTest.php

@@ -0,0 +1,48 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\VarDumper\Tests\Caster;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\VarDumper\Caster\GmpCaster;
+use Symfony\Component\VarDumper\Cloner\Stub;
+use Symfony\Component\VarDumper\Test\VarDumperTestTrait;
+
+class GmpCasterTest extends TestCase
+{
+    use VarDumperTestTrait;
+
+    /**
+     * @requires extension gmp
+     */
+    public function testCastGmp()
+    {
+        $gmpString = gmp_init('1234');
+        $gmpOctal = gmp_init(010);
+        $gmp = gmp_init('01101');
+        $gmpDump = <<<EODUMP
+array:1 [
+  "\\x00~\\x00value" => %s
+]
+EODUMP;
+        $this->assertDumpEquals(sprintf($gmpDump, $gmpString), GmpCaster::castGmp($gmpString, array(), new Stub(), false, 0));
+        $this->assertDumpEquals(sprintf($gmpDump, $gmpOctal), GmpCaster::castGmp($gmpOctal, array(), new Stub(), false, 0));
+        $this->assertDumpEquals(sprintf($gmpDump, $gmp), GmpCaster::castGmp($gmp, array(), new Stub(), false, 0));
+
+        $dump = <<<EODUMP
+GMP {
+  value: 577
+}
+EODUMP;
+
+        $this->assertDumpEquals($dump, $gmp);
+    }
+}