Add a suppression for inspector/console/console-format-es6.html flake.

TBR=jkummerow@chromium.org,yosin
BUG=432907

Review URL: https://codereview.chromium.org/722253002

git-svn-id: svn://svn.chromium.org/blink/trunk@185299 bbb929c8-8fbe-4397-9dbb-9b2b20218538