Fixes #2714: Provide non-decoded text to parse consumers

[RedHatter]

Adds a raw property to text nodes with decoded html entities set to the original data.

[Rich-Harris]

Thanks for the PR. For the sake of consistency, would it be better if chunk.raw was always set, rather than only when it differs from the decoded value?

Purely out of curiosity, what motivated this?

[jarrodldavis]

@Rich-Harris This fixes #2714 so that prettier-plugin-svelte preserves HTML entities when it formats and prints Svelte templates (see also sveltejs/prettier-plugin-svelte#29)

[Rich-Harris]

Ah, of course — the issue was already referenced 🙈

[Rich-Harris]

I took the liberty of changing the behaviour in b7f9c9c so that .raw is always added to text nodes. I find that it pays off in the end to make sure these things always behave the same way, even if it results in a larger AST

Thank you

[jarrodldavis]

If AST size is an issue, would it be better for raw to be opt-in using an option given to parse?

[Rich-Harris]

That's what I mean, I don't think it is an issue — it's rare that you'd need to serialize the AST, and memory consumption doesn't really matter since compilation happens at build time. If it were important to keep the AST small I reckon we'd want to change the design in more radical ways