Mark svg/animations/discard-check-removal-order.html as flaky in TestExpectations

BUG=333772
TBR=pavan.e@samsung.com

Review URL: https://codereview.chromium.org/136353002

git-svn-id: svn://svn.chromium.org/blink/trunk@164950 bbb929c8-8fbe-4397-9dbb-9b2b20218538