Expand slow marker to linux/mac for pub/test/serve/web_socket/url_to_asset_id_test
Expand slow marker to linux/mac for pub/test/serve/web_socket/url_to_asset_id_test

Review URL: https://codereview.chromium.org//247473002

git-svn-id: a962b240025cf0577aa172e20f49ccb159ba6be1@35259 260f80e4-7a28-3924-810f-c04153c831b5

cjkao/dart-pub,dart-lang/pub,computmaxer/pub,maxwellpeterson-wf/pub,dart-lang/pub