Enable fixed SVG LayoutTests

These previously crashing LayoutTests were fixed in r157801.

BUG=288771
BUG=266213

Review URL: https://chromiumcodereview.appspot.com/23703015

git-svn-id: svn://svn.chromium.org/blink/trunk@157956 bbb929c8-8fbe-4397-9dbb-9b2b20218538