Add support for the new function-type syntax.

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

Index: pkg/front_end/lib/src/fasta/source/diet_parser.dart
diff --git a/pkg/front_end/lib/src/fasta/source/diet_parser.dart b/pkg/front_end/lib/src/fasta/source/diet_parser.dart
index 20a1cc796cc56c4216789cc9221a80162bd105ca..82b3d14208c11baba3e862e4b1f290424d310c4a 100644
--- a/pkg/front_end/lib/src/fasta/source/diet_parser.dart
+++ b/pkg/front_end/lib/src/fasta/source/diet_parser.dart
@@ -25,7 +25,9 @@ class DietParser extends ClassMemberParser {
   DietParser(Listener listener, {bool asyncAwaitKeywordsEnabled: false})
       : super(listener, asyncAwaitKeywordsEnabled: asyncAwaitKeywordsEnabled);
 
-  Token parseFormalParameters(Token token) => skipFormals(token);
+  Token parseFormalParameters(Token token, {bool inFunctionType: false}) {
+    return skipFormals(token);
+  }
 
   Token skipFormals(Token token) {
     listener.beginOptionalFormalParameters(token);