Fold CJS_EmbedObj classes into CJS_Object classes

This CL removes the CJS_EmbedObj class and various subclasses and folds
the subclasses into their CJS_Object counterparts.

Change-Id: If6b882a4995c0b1bf83ac783f5c27ba9216c2d5c
Reviewed-on: https://pdfium-review.googlesource.com/25410
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
diff --git a/fxjs/cjs_runtime.cpp b/fxjs/cjs_runtime.cpp
index 6622695..6da52ad 100644
--- a/fxjs/cjs_runtime.cpp
+++ b/fxjs/cjs_runtime.cpp
@@ -195,11 +195,7 @@
   if (!pJSDocument)
     return;
 
-  Document* pDocument = static_cast<Document*>(pJSDocument->GetEmbedObject());
-  if (!pDocument)
-    return;
-
-  pDocument->SetFormFillEnv(m_pFormFillEnv.Get());
+  pJSDocument->SetFormFillEnv(m_pFormFillEnv.Get());
 }
 
 CPDFSDK_FormFillEnvironment* CJS_Runtime::GetFormFillEnv() const {