Cast v8::Object::GetInternalField() return value to v8::Value

In preparation of https://chromium-review.googlesource.com/c/v8/v8/+/4707972
which changes the return value to v8::Data.

Bug: v8:14120
Change-Id: I94f50f6527ab54ab1a9ef6fc75f4fc49dc32cb1a
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/110790
Reviewed-by: Nigi <nigi@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/AUTHORS b/AUTHORS
index 03f79e5..5b98287 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -46,6 +46,7 @@
 Dropbox <*@dropbox.com>
 Foxit Software Inc <*@foxitsoftware.com>
 Google Inc. <*@google.com>
+Igalia S.L. <*@igalia.com>
 LG Electronics, Inc. <*@lge.com>
 Loongson Technology Corporation Limited. <*@loongson.cn>
 Microsoft <*@microsoft.com>
diff --git a/fxjs/xfa/cfxjse_class.cpp b/fxjs/xfa/cfxjse_class.cpp
index 26b4666..c600bd7 100644
--- a/fxjs/xfa/cfxjse_class.cpp
+++ b/fxjs/xfa/cfxjse_class.cpp
@@ -103,7 +103,7 @@
   }
 
   v8::Local<v8::String> hPropName =
-      hCallBackInfo->GetInternalField(1).As<v8::String>();
+      hCallBackInfo->GetInternalField(1).As<v8::Value>().As<v8::String>();
   if (hPropName.IsEmpty())
     return;