Description:
------------
When a registered class accesses a static function that returns an empty string "", it results in a segmentation fault.

This bug appears to be distinct from #16865 since it likely has to do with type conversion, but all the software and environment settings are the same.

Reproduce code:
---------------
<?php
$app = new App();
$app->run();

class App {	
	public function run () {
		$context = new JSContext();
		$context->registerClass( 'TimeObject' );
		echo $context->evaluateScript( 'var t = new TimeObject(); t.getTime();' );
	}
	
	static function getString() {
		return ''; // <-- empty string causes seg fault
		//return ' '; // <-- a space won't cause seg fault
	}
}

class TimeObject {
	public function getTime () {
		return App::getString();
	}
}
?>

Expected result:
----------------
getTime() returns an empty string

Actual result:
--------------
Apache error_log:
[Thu Oct 08 13:43:29 2009] [notice] child pid 5629 exit signal Segmentation fault (11)