Do not eagerly convert exception to string when creating a message object

test/cctest/test-api.cc

Index: test/cctest/test-api.cc
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index e6c83849ae4881400eddc34ec268e0e51423c773..8be43313b4b9c85f2119f4483791a8c5946cb84c 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -4798,7 +4798,7 @@ TEST(APIThrowMessageOverwrittenToString) {
 
 static void check_custom_error_tostring(v8::Handle<v8::Message> message,
                                         v8::Handle<v8::Value> data) {
-  const char* uncaught_error = "Uncaught MyError toString";
+  const char* uncaught_error = "[object Object]";
   CHECK(message->Get()->Equals(v8_str(uncaught_error)));
 }