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Yes please! 👍

If you need any help feel free to ask.

This is a really important fix.
[For web js]
'transpiles' work well, but I was unable to figure out how core-js and regenerator-runtime worked, or if they were needed.
With the debug option set, I get a useBuiltIns not set warning messsage (but not which input-js/polyfills caused it).
If I set useBuiltIns, I get lots of duplicated 'import' statements in the output js (is import safe web js?)

• why not just one import each
• should the actual polyfills be included in the output js, or do i need a separate <script src=file>

I'm obviously missing something.
This might be a separate issue, but some debug message like "array.entries() needs a 50K polyfill because of safari 10.x" would be useful. Use it 100x, OK, use it once, it might be simpler to use an alternative.