Dart_PropagateError, take 2.

runtime/vm/bootstrap.h

 // 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.
 
 #ifndef VM_BOOTSTRAP_H_
 #define VM_BOOTSTRAP_H_
 
 #include "vm/allocation.h"
 
 namespace dart {
 
 // Forward declarations.
 class Library;
+class RawError;
 class RawScript;
 class Script;
 
 class Bootstrap : public AllStatic {
  public:
   static RawScript* LoadScript();
   static RawScript* LoadImplScript();
-  static void Compile(const Library& library, const Script& script);
+  static RawError* Compile(const Library& library, const Script& script);
   static void SetupNativeResolver();
 
  private:
   static const char corelib_source_[];
   static const char corelib_impl_source_[];
 };
 
 }  // namespace dart
 
 #endif  // VM_BOOTSTRAP_H_