WPT import https://crrev.com/c/1159994 introduced new failures in external/wpt/css:

List of new failures:
external/wpt/css/css-parser-api/idlharness.html new failing tests: https://crrev.com/c/1159994/4/third_party/WebKit/LayoutTests/external/wpt/css/css-parser-api/idlharness-expected.txt

This import contains upstream changes from 2c4d441493daa04906619978f4d1e9838d6b12d1 to c82a9f16b158508dd100617352c6e2e60d0910d0:
Update the CSS-Parser-API IDL file (#11978): https://github.com/web-platform-tests/wpt/commit/c82a9f16b158508dd100617352c6e2e60d0910d0 [affecting this directory]
Update buffered amount when async callbacks are called: https://github.com/web-platform-tests/wpt/commit/80f89c9af6cda0d80faf7f9b1c487eaff7205059
Update ReadableStream to match standard: https://github.com/web-platform-tests/wpt/commit/4e98c23a16efc0eb6ea4c305e3f48def3cac4643
Add tests for worker's URLs intercepted by ServiceWorker: https://github.com/web-platform-tests/wpt/commit/aaaf24402c22c34f95c676f8392f2351a433842d