Use java1.7 dx.jar. BUG=623989 Change-Id: I763eb7452c9ff417ff67ae7c77634857dc502c8a Reviewed-on: https://chromium-review.googlesource.com/394828 Reviewed-by: John Budorick <jbudorick@chromium.org> Tested-by: John Budorick <jbudorick@chromium.org>