[Feature request] Add URLSearchParams polyfill for Firefox < 44

[bjoern-tantau]

What

The URLSearchParams polyfill should be added for all Firefox versions below 44.

Details

Although URLSearchParams is available from Firefox version 29 and onwards. They only added useful features like entries() in version 44. See https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams#Browser_compatibility

Because of that one might think that there is support when only half of the features are supported.
Well, at least I did. ;-)

Workaround

if (window.URLSearchParams && !URLSearchParams.entries) {
    document.write('<script src="https://polyfill.io/v3/polyfill.min.js?flags=always&features=URL"></' + 'script>');
}

[JakeChampion]

Pull-request for this work is at #312