Its lines 120 through 124 that you need to comment, giving this:
120 /* $memory_limit = $this->return_bytes(ini_get('memory_limit')); // Memory allocated to PHP scripts
121 $suggested_memory = 12582912;
122 if ( $memory_limit < $suggested_memory ) {
123 $this->addToChecklist("Variable 'memory_limit' is $memory_limit which might not be enough for OpenGoo. You should increase it to at least $suggested_memory in your php.ini.", false);
124 } */