WPT import https://crrev.com/c/927401 introduced new failures in external/wpt/streams:

List of new failures:
[ Mac-mac10.12 ] external/wpt/streams/piping/close-propagation-forward.html new failing tests: https://crrev.com/c/927401/4/third_party/WebKit/LayoutTests/platform/mac-mac10.12/external/wpt/streams/piping/close-propagation-forward-expected.txt
[ Win ] external/wpt/streams/piping/close-propagation-forward.html new failing tests: https://crrev.com/c/927401/4/third_party/WebKit/LayoutTests/platform/win/external/wpt/streams/piping/close-propagation-forward-expected.txt
[ Mac-mac10.12 ] external/wpt/streams/piping/close-propagation-forward.serviceworker.https.html new failing tests: https://crrev.com/c/927401/4/third_party/WebKit/LayoutTests/platform/mac-mac10.12/external/wpt/streams/piping/close-propagation-forward.serviceworker.https-expected.txt
[ Win ] external/wpt/streams/piping/close-propagation-forward.serviceworker.https.html new failing tests: https://crrev.com/c/927401/4/third_party/WebKit/LayoutTests/platform/win/external/wpt/streams/piping/close-propagation-forward.serviceworker.https-expected.txt
[ Mac-mac10.12 ] external/wpt/streams/piping/close-propagation-forward.dedicatedworker.html new failing tests: https://crrev.com/c/927401/4/third_party/WebKit/LayoutTests/platform/mac-mac10.12/external/wpt/streams/piping/close-propagation-forward.dedicatedworker-expected.txt
[ Win ] external/wpt/streams/piping/close-propagation-forward.dedicatedworker.html new failing tests: https://crrev.com/c/927401/4/third_party/WebKit/LayoutTests/platform/win/external/wpt/streams/piping/close-propagation-forward.dedicatedworker-expected.txt
[ Mac-mac10.12 ] external/wpt/streams/piping/close-propagation-forward.sharedworker.html new failing tests: https://crrev.com/c/927401/4/third_party/WebKit/LayoutTests/platform/mac-mac10.12/external/wpt/streams/piping/close-propagation-forward.sharedworker-expected.txt
[ Win ] external/wpt/streams/piping/close-propagation-forward.sharedworker.html new failing tests: https://crrev.com/c/927401/4/third_party/WebKit/LayoutTests/platform/win/external/wpt/streams/piping/close-propagation-forward.sharedworker-expected.txt

This import contains upstream changes from a5a46d493b6d3ebb7a214095549874af779f2ee0 to 4c74a92846442ebb277342c3afe663a2c89955d4:
ReadableStream: test piping and queued writes: https://github.com/w3c/web-platform-tests/commit/4c74a92846442ebb277342c3afe663a2c89955d4 [affecting this directory]
Sync Mozilla tests as of https://hg.mozilla.org/mozilla-central/rev/928f0f09172fae67f6ec00e7a63969f7b28bd12e . (#9560): https://github.com/w3c/web-platform-tests/commit/5f4b60f536a95031ebacfcdfa23c3eb6d91dc294
Update supported font format specifiers: https://github.com/w3c/web-platform-tests/commit/ee2e2949929d0d371404ec5a3a7bb2873f44b34c
Pin wptrunner dependencies: https://github.com/w3c/web-platform-tests/commit/d936893f3ce7e2530994f8df62799d17cbd56dfb
Fix #8954: update wptrunner requirements: https://github.com/w3c/web-platform-tests/commit/25f040e64a77219f8e5bde319adc8561d5750823
OOR-CORS: Port WebCORSPreflightResultCacheItem to network service: https://github.com/w3c/web-platform-tests/commit/de9d5d19b70d2d8b39a9e6f9006d0a2fb4f93f53