Remove stray forward declaration of CFXJS_Engine.

It is not used on the XFA side of the house.

Change-Id: Ic1225e59a74baab83e5f3470911d7ea45e59a9e5
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/67271
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/fxjs/xfa/cfxjse_context.h b/fxjs/xfa/cfxjse_context.h
index b519e77..417cf23 100644
--- a/fxjs/xfa/cfxjse_context.h
+++ b/fxjs/xfa/cfxjse_context.h
@@ -14,7 +14,6 @@
 #include "core/fxcrt/unowned_ptr.h"
 #include "v8/include/v8.h"
 
-class CFXJS_Engine;
 class CFXJSE_Class;
 class CFXJSE_HostObject;
 class CFXJSE_Value;