inspector/elements/highlight-node-scaled.html is flakey
https://bugs.webkit.org/show_bug.cgi?id=112502

Mark this test as flakey.

* platform/mac/TestExpectations:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146002 268f45cc-cd09-0410-ab3c-d52691b4dbfc