Throw an error early when dump info is used with the startup emitter.
Throw an error early when dump info is used with the startup emitter.

The compiler will crash at the very end of the compilation with a cryptic
error message if dump info is used with the fast startup emitter.

BUG=
R=sigmund@google.com

Review URL: https://codereview.chromium.org/1866403002 .

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