5
<input type='hidden' name='timezone_offset' value='".(float)$timezone_offset."' />
That line is inside a quoted string (i.e., an echo "..."; that spans several lines), so sticking // at the beginning won't work.
Either delete the line completely, or use HTML comment delimiters:
[color=ff0000]<!--[/color]<input type='hidden' name='timezone_offset' value='".(float)$timezone_offset."' />[color=ff0000]-->[/color]
If you make other changes in that section, be careful not to mess up the outermost quotes of the echo's content.