Implement generalized function types.

pkg/compiler/lib/src/parser/element_listener.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.parser.element_listener;
 
 import 'package:front_end/src/fasta/fasta_codes.dart' show FastaMessage;
 
 import 'package:front_end/src/fasta/fasta_codes.dart' as codes;
 
@@ skipping 688 matching lines @@
         errorCode = MessageKind.UNTERMINATED_STRING;
         arguments = {"quote": arguments["string"]};
         break;
 
       case "UNTERMINATED_TOKEN":
         errorCode = MessageKind.UNTERMINATED_TOKEN;
         break;
 
       case "FASTA_IGNORED":
         return null; // Ignored. This error is already implemented elsewhere.
+
+      default:
+        throw "Unexpected message code: ${message.code}";
     }
     SourceSpan span = reporter.spanFromToken(token);
     reportError(span, errorCode, arguments);
     return null;
   }
 
   /// Finds the preceding token via the begin token of the last AST node pushed
   /// on the [nodes] stack.
   Token findPrecedingToken(Token token) {
     Token result;
@@ skipping 216 matching lines @@
       memberErrors = memberErrors.tail.prepend(true);
     }
     reporter.reportErrorMessage(spannable, errorCode, arguments);
   }
 
   void reportErrorFromToken(Token token, MessageKind errorCode,
       [Map arguments = const {}]) {
     reportError(reporter.spanFromToken(token), errorCode, arguments);
   }
 }