Fail the flutter/engine bot on analysis info items.

Change-Id: Id82ec041a924ad6f859859fafa90570ed14b69d2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/169787
Reviewed-by: Alexander Aprelev <aam@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Devon Carew <devoncarew@google.com>

Author: devoncarew

tools/bots/flutter/analyze_flutter_engine.sh

@@ -25,6 +25,8 @@ cd engine
 # analyze lib/web_ui
 echo Analyzing lib/web_ui...
 pushd lib/web_ui
+
 $dart pub get
-$dart analyze
+$dart analyze --fatal-infos
+
 popd