Bitmask-based change tracking breaks svelte-devtools

[RedHatter]

The new bitmask-based change tracking in version 3.16, while great, causes an issue with svelte-devtools. Now that the ctx object is a simple array I have no way to map the values back to their original names.

For example, previously a user might see something like this

State
string: "testing"
number: 5

Now in 3.16 they would instead see

State
0: "testing"
1: 5

One possible solution could be to expose some sort of map from ctx index to local name in dev mode.

[Conduitry]

Would this be better solved by something like #3822? I feel like we should have some official dev-only API for this, and not add a lookup that tells you how to interpret another private API.

[RedHatter]

Yeah that would both work, and would be simpler.

Though I feel like I should point out that svelte-devtools uses many private APIs. Having an official api for accessing internal ctx isn't going to change that.

[Conduitry]

Closing this in favor of #3822, which feels like it's getting pretty close to done now.

Re: using private APIs - understood, but I think there's still definitely value in gradually moving toward official APIs where it makes sense.