Attempt to fix test failure after 236915

Attempt to fix test failure after 236915
https://bugs.webkit.org/show_bug.cgi?id=190352

Unreviewed Test Gardening

LayoutTests/imported/w3c:

* web-platform-tests/WebCryptoAPI/derive_bits_keys/hkdf.https.worker-expected.txt:

LayoutTests:

* platform/mac-highsierra/hkdf.https.worker-expected.txt: Removed.
* platform/mac/imported/w3c/canvas/2d.shadow.gradient.basic-expected.png: Removed.
* platform/mac/imported/w3c/web-platform-tests/WebCryptoAPI/derive_bits_keys/hkdf.https.worker-expected.txt:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@236932 268f45cc-cd09-0410-ab3c-d52691b4dbfc