Date.toISOString() wrong result in some cases

[a-t]

Date.prototype.toISOString() used to return seconds in the milliseconds part if the latter were zero, and even a double if milliseconds were multiple of 10 or 100. Fixed it. Also removed the excessive date variable. The second commit is a workaround for IE's < 11 dates without leading zeros (e.g. 'Fri, 7 Mar 2014 08:32:15 UTC').

[triblondon]

Fixed in https://github.com/Financial-Times/polyfill-service/commit/09645f83c1d41640ae4f2ef5e2a0bfc7edffacf0. Thanks for spotting this.