Add --set-exit-code-on-problem option.

pkg/front_end/lib/compiler_options.dart

Index: pkg/front_end/lib/compiler_options.dart
diff --git a/pkg/front_end/lib/compiler_options.dart b/pkg/front_end/lib/compiler_options.dart
index 7d8a76d2294200d3f18f995e7909639ca595f2bc..3b46067f333a7355b349a2bf7de5461a50939fd3 100644
--- a/pkg/front_end/lib/compiler_options.dart
+++ b/pkg/front_end/lib/compiler_options.dart
@@ -193,4 +193,8 @@ class CompilerOptions {
   ///
   /// Dumped data is printed in stdout.
   bool debugDump = false;
+
+  /// Whether to set the exit code to non-zero if any problem (including
+  /// warning, etc.) is encountered during compilation.
+  bool setExitCodeOnProblem = false;
 }