Remove mojo download from dartium DEPS
Remove mojo download from dartium DEPS

This step is causing failures on the buildbots, so if it isn't needed,
we can remove it.  The scripts try and use gsutil in an incorrect location,
and we can no longer manually copy it because the buildbots have started
automatically removing it.

BUG=https://github.com/dart-lang/sdk/issues/28248
R=kustermann@google.com

Review-Url: https://codereview.chromium.org/2724303004 .

dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk