The method ObservatoryApplication._switchVM calls newVM.onDisconnect
and requires the resulting future to be completed with a String. In
normal operation, this is satisfied and we just need to change a few
static types to enforce it. But when FakeVM was in use, the future
was completed with `this`. Since ObservatoryApplication._switchVM is
the only call site that cares what the future is completed with, it
makes sense to just change all the types to Future<String> and modify
FakeVM accordingly.
Change-Id: Id94d27ac6a42f31ab19ccc9ad8dd270ecf4042b4
Reviewed-on: https://dart-review.googlesource.com/57400
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
Paul Berry
9e3842d624