HHVM \ReflectionFunction::getStaticVariables() incompatibility with PHP 5.4 -> 5.6

test-case.php

<?php

//See https://travis-ci.org/aztech-digital/closure-scope-merger/builds/33884775 for output containing test case

class ReflectionTest extends \PHPUnit_Framework_TestCase
{
    public function testReflectionFunctionRefVars()
    {
        $refVariable = false;
        $refName = 'refVariable';
        
        $callback = function() use (& $refVariable)
        {
            // Stub callback to get a "by-ref" variable in reflection function static vars
        };
        
        $function = new \ReflectionFunction($callback);
        $staticVariables = $function->getStaticVariables();
        
        $this->assertTrue(array_key_exists($refName, $staticVariables));
        $this->assertTrue($refVariable === false);
        
        $staticVariables[$refName] = true;
        
        $this->assertTrue($refVariable === true, 'Static variables from reflection should be bound to current scope.');    
    }
}