Detect loading to support older devices/browsers

[brokenhd]

For ie11 and ipad 5th gen 12.1.1 type devices

Some info on feature detection here: https://addyosmani.com/blog/lazy-loading/ and here https://developer.mozilla.org/en-US/docs/Web/API/HTMLImageElement

Need to make sure that lazyload is only set on the browsers that support it via 'loading' in HTMLImageElement.prototype detection.

[weotch]

Sounds like we can't trust this native load event: https://github.com/BKWLD/vue-visual/blob/master/index.vue#L43. I'm hoping we can find a good poly/pony-fill for that so we don't have to just ditch lazy loading ... but that's not terrible either IMO since it's a smallish set and not really breaking functionality.