Consider adding a mode which doesn't use Blobs

[mstange]

When running JetStream in the browser, prefetchResourcesForBrowser turns all JS URLs into blob URLs.

These blob URLs make profiling significantly harder.

For example, https://webkit-jetstream-preview.netlify.app/cdjs/call_sign.js
might become blob:https://webkit-jetstream-preview.netlify.app/b151b0cb-69f0-4d3d-a764-80edb3af7d65

Losing the original path makes it harder to look up the source code based on profiles.
Furthermore, the UUIDs in the Blob URL are different in each run, which makes it harder to compare the runtime of a function between runs.

Could we have a mode which doesn't throw away the JS URLs?

For example, we could add a noPreload query parameter, so that when running e.g. https://webkit-jetstream-preview.netlify.app/?noPreload, we would skip the call to prefetchResourcesForBrowser.

[Constellation]

One of the issue we found before was, if we do some networking during tests, it may stall main process, making CPU p-state lower due to wait for IO, and drastically changing the results. So current Blob approach ensuring downloading all binaries before test running is critical for the correctness of the measurement.

[LeszekSwirski]

+1 to some solution to this, I've had the same issue with looking up source code based on profiles, or similarly in trying to merge multiple profiles together.