Expose svelte version in dev mode

[RedHatter]

It would be helpful to be able to determine what version of svelte a given bundle was build with. This would simplify attempting to support both old and new versions of svelte in svelte-devtools. This hasn't been an issue so far but I'm sure it eventually will as new version change the internals more.

I'm not quite sure where this would be exposed though.

[antony]

I notice that the compiled output has /* App.svelte generated by Svelte v3.16.5 */ at the top of it.

Would it be possible to use this to determine version? Or would it be better to have a concrete version attribute exposed in the dev source?

[RedHatter]

@antony There's no easy/reliable way to access the raw source of the bundle.

One way to expose this would be in the dev event details. For example.

	dispatch_dev("SvelteRegisterBlock", {
		block,
		id: create_each_block.name,
		type: "each",
		source: "(4:0) {#each things as thing, index}",
		ctx,
                version: "3.16.5"
	});

[antony]

@RedHatter gotcha. I've been looking at doing something similar this morning.

[Conduitry]

This is now exposed in 3.17.0. Thanks!