ob_start() implementation not 5.4 compatible.

[arjenschol]

Still has 3rd parameter boolean $erase.
Since 5.4 ob_start has the following signature:
bool ob_start ([ callable $output_callback = NULL [, int $chunk_size = 0 [, int $flags = PHP_OUTPUT_HANDLER_STDFLAGS ]]] )

See http://php.net/manual/en/function.ob-start.php#refsect1-function.ob-start-changelog

[JoelMarcey]

Internal diff: D1677599