Description:
------------
The GD functions imagettfbbox() returns FALSE for various errors
such as a missing $fontfile. This return value is undocumented at:

  <http://se2.php.net/manual/en/function.imagettfbbox.php>

Same problem for imagettftext():

  <http://se2.php.net/manual/en/function.imagettftext.php>

(The results are from PHP 5.2.5 but recently downloaded source
 code for 5.3.0 contain several RETURN_FALSE.)


Reproduce code:
---------------
<?php

  $r = imagettfbbox (10, 0, 'no-such-font.ttf', 'Test string');
  echo PHP_VERSION, "\n";
  var_dump ($r);


Expected result:
----------------
5.2.5
bool(false)


Actual result:
--------------
5.2.5
bool(false)