tests: update many test traces, support .json.gz

[connorjclark]

Updates many old test traces. Also adds .json.gz support to asset-saver.js. I wanted to add fixtures for cnn.com, but they were far too big to commit without compression.

ref #15841

[brendankenny]

Would it be better to use a more controlled trace to replace this? I don't envy the next person making changes to the simulator having to manually determine if any changes to these numbers are reasonable from a massive cnn trace.

Alternatively, if it needs to be more complex than what's in our smoke tests, in #14525 we had discussed using the test sites in https://github.com/ChromeDevTools/performance-stories as the source of generating test artifacts. Controlled, intentional, but also a decent variety of scenarios.

[connorjclark]

I don't see any story there that has much JS work going on.

I can switch to something else. intercom-widget has a value here. But I don't know why for observed I'm getting this:

  1) Metrics: TotalBlockingTime
       should compute an observed value:
     LighthouseError: NO_TTI_CPU_IDLE_PERIOD
      at Interactive.findOverlappingQuietPeriods (file:///Users/cjamcl/src/lighthouse/core/computed/metrics/interactive.js:134:11)
      at Interactive.computeObservedMetric (file:///Users/cjamcl/src/lighthouse/core/computed/metrics/interactive.js:164:41)
      at Interactive.compute_ (file:///Users/cjamcl/src/lighthouse/core/computed/metrics/metric.js:91:21)

I wonder if user flows are ending too early?

[connorjclark]

@paulirish and I investigated the NO_TTI error and found an unrelated issue