Meta bug for tracking performance benchmarks for Web Components.

It would be nice that we have the following benchmarks, but not limited to:

- Benchmarks which use telemetry. We should track the performance of applications which use Web Components in real world, to figure out points which should be improved.
- Basic metrics related to Web Components + some metrics for measuring more complex stories which we do not have data
- Page sets which uses Web Components
- Micro benchmarks to track particular scenarios, such as the performance of distributions, the benefits of selector matching in each shadow trees, and so on

It would be also nice to compare non-WebComponents applications vs Web Components applications with the same capabilities.