Changed Slick Carousel lazyLoad technique to Anticipated.

[Ubersmake]

What?

Cornerstone has an issue where the first image in a carousel appears to reload on wrap. This "reload" happens despite the browser not making any new GETs.

This behavior is fixed by changing the Slick Carousel's lazy load technique back from ondemand to anticipated.

Slick Carousel's documentation has, at time of this PR, removed mentions of anticipated as a lazyLoad technique: https://github.com/kenwheeler/slick/blob/a2aa3fec335c50aceb58f6ef6d22df8e5f3238e1/README.markdown. The only two documented options are ondemand and progressive. progressive is markedly worse than ondemand in terms of performance. However, anticipated is still used to determine logic in slick.js, in both 1.8.1 and 1.9.0:

1.8.1: https://github.com/kenwheeler/slick/blob/ee7d37faeb92c4619ffeefeba2cc4c733f39b1b3/slick/slick.js
1.9.0: https://github.com/kenwheeler/slick/blob/a2aa3fec335c50aceb58f6ef6d22df8e5f3238e1/slick/slick.js

This PR comes after digging into Slick Carousel with #1259.

Tickets / Documentation

• Slick Carousel
• STRF-4979
• Lighthouse Report Viewer

Screenshots and Reports

Reports were done on a test store. These stores are light, with very few products and zero customizations. The margin in performance should be significantly wider on a live store.

These reports were generated by Lighthouse and can be viewed in a human-readable form at https://googlechrome.github.io/lighthouse/viewer2x/.

Before: ondemand

ondemand.txt

After: anticipated

anticipated.txt

[bigbot]

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