Mark inspector/console/console-timeline.html as flaky on all platforms.

TBR=wjmaclean@chromium.org
BUG=299819

Review URL: https://codereview.chromium.org/25048003

git-svn-id: svn://svn.chromium.org/blink/trunk@158456 bbb929c8-8fbe-4397-9dbb-9b2b20218538