Make run-bindings-tests quiet by default

Currently run-bindings-tests always outputs success messages.
This makes it hard to debug the failures.
This CL makes them quiet by default (only show failures),
and adds a --verbose option to get current behavior.

This should also make presubmit script errors easier to understand.

Review URL: https://codereview.chromium.org/55673002

git-svn-id: svn://svn.chromium.org/blink/trunk@161145 bbb929c8-8fbe-4397-9dbb-9b2b20218538