Scripts: Upgrade Babel to the new minor version (7.10.x)

[gziolo]

Description

Babel 7.10.0 was release:

https://babeljs.io/blog/2020/05/25/7.10.0

One of the highlighted features is Better tree-shaking for React components:

React exposes many pure functions used to annotate or wrap elements, for example React.forwardRef, React.memo or React.lazy. However, minifiers and bundlers aren't aware that these functions are pure and thus they cannot remove them.

Thanks to Devon from the Parcel team, @babel/preset-react now injects /*#__PURE__*/ annotations in those functions calls to mark them as being safe to be tree-shaken away. We had only previously done this with JSX itself (<a></a> => /*#__PURE__*/React.createElement("a", null))

We don't use @babel/preset-react but I'm still wondering if this work could bring some performance gains.

References

It might be helpful to look at previous PR where minor version upgrade for Babel was applied: #21419. The changes that might be required:

• all Babel related packages in @wordpress/babel-preset-default
• Babel packages in the root package.json file
• upgrading babel-loader in @wordpress/scripts
• upgrading @babel/runtime in multiple packages