add_editor_style is not loading in frontend. Any solution?

This is default wordpress add_editor_style function:

function add_editor_style( $stylesheet="editor-style.css" ) {

    add_theme_support( 'editor-style' );

    if ( ! is_admin() )
        return;

    global $editor_styles;
    $editor_styles = (array) $editor_styles;
    $stylesheet    = (array) $stylesheet;
    if ( is_rtl() ) {
        $rtl_stylesheet = str_replace('.css', '-rtl.css', $stylesheet[0]);
        $stylesheet[] = $rtl_stylesheet;
    }

    $editor_styles = array_merge( $editor_styles, $stylesheet );
}

As you see if ( ! is_admin() ) return; is there and basically we cant add custom styles to frontend wp_editor.. What is proper solution for it?

Here is my solution:

add_filter('the_editor_content', "firmasite_tinymce_style");
function firmasite_tinymce_style($content) {
    add_editor_style('assets/css/custom.css');

    // This is for front-end tinymce customization
    if ( ! is_admin() ) {
        global $editor_styles;
        $editor_styles = (array) $editor_styles;
        $stylesheet    = (array) $stylesheet;

        $stylesheet[] = 'assets/css/custom.css';

        $editor_styles = array_merge( $editor_styles, $stylesheet );

    }
    return $content;
}

Live Example: http://unsalkorkmaz.com/firmasite-social-buddypress-bbpress-theme-based-on-bootstrap/
Check comments wp_editor.. its loading bootstrap.css and google fonts etc..

This code is extra:

// Removing wordpress version from script and styles
add_action("wp_head", "firmasite_remove_version_from_assets",1);
function firmasite_remove_version_from_assets(){
    function remove_cssjs_ver( $src ) {
        if( strpos( $src, '?ver=" ) )
            $src = remove_query_arg( "ver', $src );
        return $src;
    }
    add_filter( 'style_loader_src', 'remove_cssjs_ver', 999 );
    add_filter( 'script_loader_src', 'remove_cssjs_ver', 999 );
}

Its removing version from styles and scripts. So browser wont load same style double times.