The type attribute is unnecessary for javascript resources

To remove the type attribute, simply paste this code into your theme file.

add_action( 'template_redirect', 'safe_remove_template_redirect', 10, 2);

function saf_remove_template_redirect(){
  ob_start( function( $buffer ){
    $buffer = str_replace( array( 
        '<script type="text/javascript">',
        "<script type='text/javascript'>", 
        "<script type='text/javascript' src=",
        '<script type="text/javascript" src=',
        '<style type="text/css">', 
        "' type='text/css' media=", 
        '<style type="text/css" media',
        "' type='text/css'>"
    ), 
    array(
        '<script>', 
        "<script>", 
        "<script src=",
        '<script src=',
        '<style>', 
        "' media=", 
        '<style media',
        "' >"
    ), $buffer );

    return $buffer;
  });
};