core(fr): timespan ensure bytes transferred

[adamraine]

So I was playing around with FR for fun and I ran into an issue with byte efficiency audits.

This time, we were hitting:

lighthouse/lighthouse-core/lib/dependency-graph/simulator/network-analyzer.js

Line 348 in 6c3d609

if (!estimatesByOrigin.size) throw new Error('No timing information available');

The first timespan in the flow ("Open search menu") generated ~6 network requests but they all had a transferSize of 0 so NetworkAnalyzer threw this error when creating the LoadSimulator. The simplest solution was to ensure some bytes were transferred in order to make timespan BE audits applicable.

This isn't a problem in navigations, because the main resource guarantees a nonzero total transfer size.

[patrickhulce]

🎉 nice find!