I am building a webcomponent based application and I am eliminating unnecessary code in my bundles. To compile es5 elements, I've added the webcomponentsjs polyfills and it suggested two script files to attach:
"node_modules/@webcomponents/webcomponentsjs/bundles/webcomponents-sd-ce-pf.js"
"node_modules/@webcomponents/webcomponentsjs/custom-elements-es5-adapter.js"
It seems I can't get away without the adapter but it seems to be working fine without webcomponents-sd-ce-pf.js. I'd like to ask about its purpose. The documentation seems to be a bit vague about it.
if you want to support IE or (legacy) Edge you will need it.