Build blink_platform_unittests and wtf_unittests on Android

BUG=none
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/186863002

git-svn-id: svn://svn.chromium.org/blink/trunk@168505 bbb929c8-8fbe-4397-9dbb-9b2b20218538