Do not deoptimize entire super class when adding a property

[lukastaegert]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:

Description

We do not want to deoptimize the entire super class when adding a property, it is enough to deoptimize just properties of the given path (actually in a manner of speaking we may not need to deoptimize at all but deoptimization is a more general concept than reassignment and there may be some edge cases we need to cover).

Following a discussion in Twitter https://twitter.com/pschroen/status/1522269915864256512?s=20&t=8igcqT2KuKkLKgGP3hjvVA, see https://rollupjs.org/repl/?version=2.71.1&shareable=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

[github-actions]

Thank you for your contribution! ❤️

You can try out this pull request locally by installing Rollup via

npm install rollup/rollup#deoptimize-superclass

or load it into the REPL:
https://rollupjs.org/repl/?pr=4489

[codecov]

Codecov Report

Merging #4489 (f53f23f) into master (19aef13) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #4489   +/-   ##
=======================================
  Coverage   98.72%   98.72%           
=======================================
  Files         206      206           
  Lines        7351     7351           
  Branches     2086     2086           
=======================================
  Hits         7257     7257           
  Misses         34       34           
  Partials       60       60           

Impacted Files	Coverage Δ
src/ast/nodes/shared/ObjectEntity.ts	100.00% <100.00%> (ø)

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[pschroen]

Confirmed to be working locally with rollup/rollup#deoptimize-superclass and my test bundle.

Note the thread originally started with tree-shaking the flat three.module.js bundle with Webpack, and even with this update Rollup is unable to tree-shake the bundle, there are multiple side effects at play here including use of Object.defineProperties outside of the classes (mrdoob/three.js#24006).

I'll leave it up to you if you'd like to close this issue as resolved and we can let you know if anything new comes up?

[lukastaegert]

I think I will just merge this. I might also be able to improve handling of Object.defineProperties in the next days, there is some low-hanging fruit.