Ponyfill to fix element.classList browser inconsistencies.

• Fixes multiple arguments for add()/remove()
• Adds missing force argument for toggle()
• Shadows contains()/replace() for convenience.

Note: does not fix missing classList on SVG/MathML elements on some platforms.

Usage

import { addClass, removeClass, toggleClass } from '@yr/classlist';

// Add/remove multiple classes
addClass(element, 'foo', 'bar');
removeClass(element, 'foo', 'bar');
// Respect 'force' argument
toggleClass(element, 'foo', Math.random() > 0.5);