Migrated tests to jest

Used jest-codemods to migrate, will have to pass everything by hand before we can merge.

test/on/on.js

@@ -1,6 +0,0 @@
-const on = (el, evt, fn, opts = {}) => {
-const delegatorFn = e => e.target.matches(opts.target) && fn.call(e.target, e);
-el.addEventListener(evt, opts.target ? delegatorFn : fn, opts.options || false);
-if (opts.target) return delegatorFn;
-};
-module.exports = on;