Get tests passing on 1.14.
Get tests passing on 1.14.

This skips one test that's broken by dart-lang/sdk#25379, and makes a
test that relied on dart:async not being loaded during startup use a
non-existent user library instead.

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//1578003003 .

dart-archive/vm_service_client