perf: optimize scoped ID for light/native

[nolanlawson]

Details

Fixes #3658.

This avoids rendering the genScopedId function (aka gid aka global ID) or scopedFragId (aka fid aka fragment ID) for light DOM templates or shadow DOM templates when disableSyntheticShadowSupport is true. These functions only do anything in synthetic shadow DOM mode:

lwc/packages/@lwc/engine-core/src/framework/api.ts

Lines 580 to 582 in 84e0536

	if (shadowMode === ShadowMode.Synthetic) {
	return StringReplace.call(id, /\S+/g, (id) => `${id}-${idx}`);
	}

lwc/packages/@lwc/engine-core/src/framework/api.ts

Lines 606 to 608 in 84e0536

	if (shadowMode === ShadowMode.Synthetic && /^#/.test(url)) {
	return `${url}-${idx}`;
	}

None of our existing benchmarks are able to suss out the perf improvement. I did write a benchmark (nolanlawson@1599b49) which demonstrates the improvement, but I felt it was too tailored to this PR to make sense to commit to master. Here is the improvement (6-9%):

Here is a before-and-after to show what the compiled template looks like before and after this change. Note that on the right, everything is moved into static HTML fragments:

Does this pull request introduce a breaking change?

• 😮‍💨 No, it does not introduce a breaking change.

Does this pull request introduce an observable change?

• 🤞 No, it does not introduce an observable change.

Since the gid/fid functions only do anything in synthetic shadow DOM, disabling them for light DOM or native shadow should be un-observable.

[nolanlawson]

I got rid of these logErrors because they seemed pretty low-value (only logged in dev mode, should arguably be the job of accessibility tools like aXe, not LWC), and I couldn't think of a good way to maintain the dev-only logging when the optimization is in place.

[nolanlawson]

Just another case I think is worth testing, especially if we start actually shipping disableSyntheticShadowSupport=true.

[wjhsf]

Eagerly anticipating another chore(ci): rebalance karma tests

[nolanlawson]

You guessed it! It's imbalanced again. I wish GH had an easier way to do this. 🫠

[wjhsf]

Eagerly anticipating another chore(ci): rebalance karma tests