Mark svg/as-image/animated-svg-animation-control.html as flaky

BUG=356742
TBR=fs@opera.com

Review URL: https://codereview.chromium.org/213153004

git-svn-id: svn://svn.chromium.org/blink/trunk@170070 bbb929c8-8fbe-4397-9dbb-9b2b20218538