ensure wasm tests are doing what we want, both locally and in CI

[phritz]

1. wasm bench
   • doesn't compile eg ./tool/benchmark |tee > wasm-bench.txt
   • when it fails in CI it still is shown as green. go to https://github.com/rocicorp/repc/runs/1974200630?check_suite_focus=true, click wasm size, click the tool/benchmark step and scroll down
   • probably we should just remove this test, but also worth understanding why it doesn't fail CI when it broke
2. wasm size
   • https://github.com/rocicorp/repc/runs/1974200598?check_suite_focus=true click on wasm size, click the run tool/release --report item and scroll down. it is failing. we want CI to fail if it fails
   • need to verify that it works locally too