report const class as a more specific error code

pkg/front_end/lib/src/fasta/fasta_codes_generated.dart

Index: pkg/front_end/lib/src/fasta/fasta_codes_generated.dart
diff --git a/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart b/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart
index f50d239a89a531b24ffb1ca43098d6e9b628c60c..5ece41d025f4b9b78eb8cb50a6c34194a48a6a27 100644
--- a/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart
+++ b/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart
@@ -364,6 +364,17 @@ const MessageCode messageConflictsWithTypeVariableCause = const MessageCode(
     "ConflictsWithTypeVariableCause",
     message: r"""This is the type variable.""");
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeConstClass = messageConstClass;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageConstClass = const MessageCode("ConstClass",
+    analyzerCode: "CONST_CLASS",
+    dart2jsCode: "EXTRANEOUS_MODIFIER",
+    message: r"""Classes can't be declared to be 'const'.""",
+    tip:
+        r"""Try removing the 'const' keyword. If you're trying to indicate that instances of the class can be constants, place the 'const' keyword on  the class' constructor(s).""");
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeConstConstructorNonFinalField =
     messageConstConstructorNonFinalField;