Throw exceptions for errors in v8::ValueSerializer.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 713bbccd544c3c4c2d3a45a63ee2782bd6345cb7..616dc921e3dee0341a087f9793c964168b457c0b 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -1670,7 +1670,20 @@ class V8_EXPORT JSON {
  */
 class V8_EXPORT ValueSerializer {
  public:
+  class V8_EXPORT Delegate {
+   public:
+    virtual ~Delegate() {}
+
+    /*
+     * Handles the case where a DataCloneError would be thrown in the structured
+     * clone spec. Other V8 embedders may throw some other appropriate exception
+     * type.
+     */
+    virtual void ThrowDataCloneError(Local<String> message) = 0;
+  };
+
   explicit ValueSerializer(Isolate* isolate);
+  ValueSerializer(Isolate* isolate, Delegate* delegate);
   ~ValueSerializer();
 
   /*