feat(client): introduce core-js

[hiroppy]

• This is a bugfix
• This is a feature
• This is a code refactor
• This is a test update
• This is a docs update
• This is a metadata update

For Bugs and Features; did you add new tests?

modify only

Motivation / Use-Case

#1948 (comment)

Breaking Changes

no

Additional Info

[alexander-akait]

We pollute global namespace 😞 We should use named import like in docs https://github.com/zloirock/core-js

[hiroppy]

sorry, why?

[alexander-akait]

Maybe we need setup support import/export in our babel config for client too

[alexander-akait]

Using require('core-js/features/array/includes'); modify Array.prototype, so if developer already have modified Array.prototype we break can break their app. Using import arrayIncludes from 'core-js/features/array/includes' doesn't modify Array.prototype so it is safe to use

[hiroppy]

Makes sense. ok, I'll change

[hiroppy]

@evilebottnawi updated, PTAL

[codecov]

Codecov Report

Merging #1950 into next will increase coverage by 0.01%.
The diff coverage is 75%.

@@            Coverage Diff             @@
##             next    #1950      +/-   ##
==========================================
+ Coverage   92.61%   92.62%   +0.01%     
==========================================
  Files          29       30       +1     
  Lines        1124     1126       +2     
  Branches      325      325              
==========================================
+ Hits         1041     1043       +2     
  Misses         79       79              
  Partials        4        4

Impacted Files	Coverage Δ
client-src/default/polyfill.js	100% <100%> (ø)
client-src/default/index.js	91.56% <50%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9c5f6bb...3ea39ad. Read the comment docs.

[alexander-akait]

Looks good! Before merge please manually check what we don't modify global built-in (just looks in client and this file should not have any String.prototype or Array.prototype)

[hiroppy]

I'll create other new pr.