Allow constants as field initial values as well as creation thunks

lib/src/protobuf/generated_message.dart

 // Copyright (c) 2011, 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.
 
 part of protobuf;
 
 typedef GeneratedMessage CreateBuilderFunc();
 typedef Object MakeDefaultFunc();
 typedef ProtobufEnum ValueOfFunc(int value);
 
@@ skipping 471 matching lines @@
         case _OPTIONAL_FLOAT:
           _fieldValues[tagNumber] = input.readFloat();
           break;
         case _OPTIONAL_DOUBLE:
           _fieldValues[tagNumber] = input.readDouble();
           break;
         case _OPTIONAL_ENUM:
           int rawValue = input.readEnum();
           var value = _getValueOfFunc(tagNumber, extensionRegistry)(rawValue);
           if (value == null) {
-            unknownFields.mergeVarintField(tagNumber, makeLongInt(rawValue));
+            unknownFields.mergeVarintField(tagNumber, new Int64(rawValue));
           } else {
             _fieldValues[tagNumber] = value;
           }
           break;
         case _OPTIONAL_GROUP:
           GeneratedMessage subMessage =
               _getEmptyMessage(tagNumber, extensionRegistry);
           if (_fieldValues.containsKey(tagNumber)) {
             subMessage.mergeFromMessage(getField(tagNumber));
           }
@@ skipping 54 matching lines @@
           readPackable(wireType, tagNumber, input.readFloat);
           break;
         case _REPEATED_DOUBLE:
           readPackable(wireType, tagNumber, input.readDouble);
           break;
         case _REPEATED_ENUM:
           readPackableIoc(wireType, tagNumber, (var assigner){
             int rawValue = input.readEnum();
             var value = _getValueOfFunc(tagNumber, extensionRegistry)(rawValue);
             if (value == null) {
-              unknownFields.mergeVarintField(tagNumber, makeLongInt(rawValue));
+              unknownFields.mergeVarintField(tagNumber, new Int64(rawValue));
             } else {
               assigner(value);
             }
           });
           break;
         case _REPEATED_GROUP:
           GeneratedMessage subMessage =
               _getEmptyMessage(tagNumber, extensionRegistry);
           input.readGroup(tagNumber, subMessage, extensionRegistry);
           List list = getField(tagNumber);
@@ skipping 658 matching lines @@
               _generateMessage(tagNumber, value, 'not a GeneratedMessage'));
         }
         break;
       default:
         throw new ArgumentError(
             _generateMessage(tagNumber, value, 'field has unknown type '
             '$fieldType'));
     }
   }
 }