Update internal generated files

lib/src/plugin.pb.dart

 ///
 //  Generated code. Do not modify.
 ///
-library Plugin.pb;
+library proto2.compiler;
 
 import 'dart:typed_data';
 
+import 'package:fixnum/fixnum.dart';
 import 'package:protobuf/protobuf.dart';
 import 'descriptor.pb.dart';
 
 class CodeGeneratorRequest extends GeneratedMessage {
   static final BuilderInfo _i = new BuilderInfo('CodeGeneratorRequest')
     ..p(1, 'fileToGenerate', GeneratedMessage.PS)
     ..a(2, 'parameter', GeneratedMessage.OS)
     ..m(15, 'protoFile', () => new FileDescriptorProto(), () => new PbList<FileDescriptorProto>())
+    ..hasRequiredFields = false
   ;
 
   CodeGeneratorRequest() : super();
   CodeGeneratorRequest.fromBuffer(List<int> i, [ExtensionRegistry r = ExtensionRegistry.EMPTY]) : super.fromBuffer(i, r);
   CodeGeneratorRequest.fromJson(String i, [ExtensionRegistry r = ExtensionRegistry.EMPTY]) : super.fromJson(i, r);
   CodeGeneratorRequest clone() => new CodeGeneratorRequest()..mergeFromMessage(this);
   BuilderInfo get info_ => _i;
 
   List<String> get fileToGenerate => getField(1);
 
@@ skipping 49 matching lines @@
   BuilderInfo get info_ => _i;
 
   String get error => getField(1);
   void set error(String v) { setField(1, v); }
   bool hasError() => hasField(1);
   void clearError() => clearField(1);
 
   List<CodeGeneratorResponse_File> get file => getField(15);
 }