Add 'data' to copy() to for swarm-testing to work on trybots.
Otherwise, the ICU data bundle would not be copied in isolate_tests step and
all the tests requiring the ICU data would fail on trybots.

BUG=v8:4828
TEST=base_unittests and many other tests pass on trybots (with test isolation)
R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/2197523002 .