Prepare for development branch by updating externally-used API.

pkg/front_end/lib/src/fasta/source/diet_listener.dart

Index: pkg/front_end/lib/src/fasta/source/diet_listener.dart
diff --git a/pkg/front_end/lib/src/fasta/source/diet_listener.dart b/pkg/front_end/lib/src/fasta/source/diet_listener.dart
index 00414f30916bc232890dcbdaa9b4a161b261875d..1c55c6ea42041591ca83e1db3a599335e3ad1a0b 100644
--- a/pkg/front_end/lib/src/fasta/source/diet_listener.dart
+++ b/pkg/front_end/lib/src/fasta/source/diet_listener.dart
@@ -585,6 +585,14 @@ class DietListener extends StackListener {
   }
 
   @override
+  void addCompileTimeErrorFromMessage(FastaMessage message) {
+    library.addCompileTimeError(message.charOffset, message.message,
+        fileUri: message.uri,
+        // We assume this error has already been reported by OutlineBuilder.
+        silent: true);
+  }
+
+  @override
   void debugEvent(String name) {
     // printEvent(name);
   }