Update parser to not check that all final fields are initialized for external constructors.

runtime/vm/parser.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_PARSER_H_
 #define VM_PARSER_H_
 
 #include "include/dart_api.h"
 
 #include "vm/ast.h"
@@ skipping 307 matching lines @@
   void CheckDuplicateFieldInit(intptr_t init_pos,
                                GrowableArray<Field*>* initialized_fields,
                                Field* field);
   void GenerateSuperConstructorCall(const Class& cls,
                                     LocalVariable* receiver);
   AstNode* ParseSuperInitializer(const Class& cls, LocalVariable* receiver);
   AstNode* ParseInitializer(const Class& cls,
                             LocalVariable* receiver,
                             GrowableArray<Field*>* initialized_fields);
   void ParseConstructorRedirection(const Class& cls, LocalVariable* receiver);
+  void CheckNoInitializersInExternal();
   void ParseInitializers(const Class& cls,
                          LocalVariable* receiver,
                          GrowableArray<Field*>* initialized_fields);
   String& ParseNativeDeclaration();
   // TODO(srdjan): Return TypeArguments instead of Array?
   RawArray* ParseInterfaceList();
   void AddInterfaces(intptr_t interfaces_pos,
                      const Class& cls,
                      const Array& interfaces);
   ArgumentListNode* BuildNoSuchMethodArguments(
@@ skipping 232 matching lines @@
 
   // Allocate temporary only once per function.
   LocalVariable* expression_temp_;
 
   DISALLOW_COPY_AND_ASSIGN(Parser);
 };
 
 }  // namespace dart
 
 #endif  // VM_PARSER_H_