Avoiding use of eval

[bakkot]

cf nodejs/node#61078, there is a use of eval for converting string literals to their values, which doesn't work under --disallow-code-generation-from-strings.

Would you take a PR fixing this? I can port an existing string literal parser from Shift or Babel. And I can add a fast path using JSON.parse which will work almost all of the time, with the more complex parser needed only for fallback.

[aduh95]

I don't think we can promise taking a PR without being able to look at it and what tradeoffs if any it involves.

One thing I wonder is whether WASM is (still?) a good fit, or if it wouldn't simpler to port the C code in Node.js source and have access to e.g. V8 APIs or even just acorn parser.

[guybedford]

@bakkot I would be happy to review and publish a PR here to help move things forward.

A C/C++ port would still be great to see, but in the mean time we should make sure to support existing users.