Enable breakpad on linux when running layout tests

Unexpected crashes should have fully symbolized stack traces.

BUG=253351
R=dpranke@chromium.org

Review URL: https://codereview.chromium.org/59493002

git-svn-id: svn://svn.chromium.org/blink/trunk@161446 bbb929c8-8fbe-4397-9dbb-9b2b20218538