Currently, when w3c tests are imported (via the update-w3c-deps script), new common resource files (e.g. idlharness.js, testharness.js) can be updated which can affect other non-imported tests.

For example: https://codereview.chromium.org/2448433002

When update-w3c-deps --auto-import runs it invokes update-w3c-test-expectations, which currently explicitly looks only at tests starting with "imported/".

If resource files are updated, update-w3c-test-expectations could also update any expectations or baselines for other tests, not just newly imported and updated tests.

Now, since we can fetch the try job retry summary, we should be able to try to just update expectations for tests that failed with the patch but not without, which should decrease the probability of an unaffected flaky test's expectations getting updated.