enable --dump-info with the --fast-startup emitter

pkg/compiler/lib/src/js_emitter/lazy_emitter/emitter.dart

Index: pkg/compiler/lib/src/js_emitter/lazy_emitter/emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/lazy_emitter/emitter.dart b/pkg/compiler/lib/src/js_emitter/lazy_emitter/emitter.dart
index a38de703e23ede7fd1067fda4b7ff51a11021573..09105b8d09275ba6d0b9cc1bb5236b4b0f363fc7 100644
--- a/pkg/compiler/lib/src/js_emitter/lazy_emitter/emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/lazy_emitter/emitter.dart
@@ -9,6 +9,7 @@ import 'package:js_runtime/shared/embedded_names.dart' show JsBuiltin;
 import '../../common.dart';
 import '../../compiler.dart' show Compiler;
 import '../../constants/values.dart' show ConstantValue;
+import '../../deferred_load.dart' show OutputUnit;
 import '../../elements/elements.dart'
     show ClassElement, Element, FieldElement, FunctionElement;
 import '../../js/js.dart' as js;
@@ -188,5 +189,9 @@ class Emitter implements emitterTask.Emitter {
   }
 
   @override
+  // TODO(het): Generate this correctly
+  int generatedSize(OutputUnit unit) => 0;
+
+  @override
   void invalidateCaches() {}
 }