Combokeys

The purpose of this file is to throw the Keysim module up to global `window.Keysim`.

As the comment reads, it can't be used in IE8 and older. So it does so conditionally.

Obviously, the code gets browserified regardless or the browser.

The fact that the `require("keysim")` isn't called in these browsers, prevents that code from running. Thus the exception due to the missing `defineProperty` isn't encountered at all.