Gardening: Mark RTCPeerConnection-lifetime.html crashy

TBR=tommyw@chromium.org
BUG=349528

Review URL: https://codereview.chromium.org/187413005

git-svn-id: svn://svn.chromium.org/blink/trunk@168514 bbb929c8-8fbe-4397-9dbb-9b2b20218538