In addition to wpt/workers, there are some Fetch+Worker-related test failures, e.g. under wpt/fetch.

https://codesearch.chromium.org/search/?q=worker-expected.txt+file:%5Esrc/third_party/WebKit/LayoutTests/external/wpt/fetch/+package:%5Echromium$&type=cs

Some of them are not worker-specific (i.e. also failing on Document), but anyway we have to check/triage them.
This will be helpful for off-the-main-thread fetches as this confirms test coverage.