Issue loading pdf generated from FPDI

Having some difficultly loading a pdf from dev-master which I'm doing at the moment due to needing the code change in #450

The pdf was created in FPDI.

When calling getDetails() I'd expect to be able to get the MediaBox of the page, but it's not there any more.

$parser = new Parser();
$pdf = $parser->parseFile(__DIR__.'/../../test2.pdf');
$pages = $pdf->getPages();
foreach ($pages as $i => $page) {
    $details = $page->getDetails();
    var_dump($details);
}

Any help would be amazing

Pdf used: test2.pdf

Output of getDetails:

array(5) {
  ["Type"]=>
  string(4) "Page"
  ["Parent"]=>
  array(2) {
    ["Type"]=>
    string(5) "Pages"
    ["Count"]=>
    string(1) "1"
  }
  ["Resources"]=>
  array(0) {
  }
  ["Group"]=>
  array(3) {
    ["Type"]=>
    string(5) "Group"
    ["S"]=>
    string(12) "Transparency"
    ["CS"]=>
    string(9) "DeviceRGB"
  }
  ["Contents"]=>
  array(2) {
    ["Filter"]=>
    string(11) "FlateDecode"
    ["Length"]=>
    string(3) "106"
  }
}

Reproduce the report with the attached test2.pdf using Parser->parseFile(), then inspect the page returned by getPages() and its getDetails() output. Trace how page details are exposed and confirm that the expected MediaBox is available for this FPDI-generated PDF.