[SVG] Deflake repeatn-event-1b.svg and repeatn-event-1d.svg

svg/animations/repeatn-event-1b.svg and svg/animations/repeatn-event-1d.svg
are currently flaky on our trybots particularly the debug and asan bots.
This patch increases reliability by bumping the timeout from 10ms to 30ms.

R=pdr@chromium.org, schenney@chromium.org, dschulze@chromium.org, fmalita@chromium.org, rob.buis@samsung.com
BUG=333791

Review URL: https://codereview.chromium.org/148383002

git-svn-id: svn://svn.chromium.org/blink/trunk@165869 bbb929c8-8fbe-4397-9dbb-9b2b20218538