Merge to XFA: Fix (nearly all) IWYU in fpdfskd/include/javascript/ headers.

Original Review URL: https://codereview.chromium.org/1060133002
TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/1065103002
diff --git a/fpdfsdk/include/javascript/JS_Object.h b/fpdfsdk/include/javascript/JS_Object.h
index f30bc17..74af9ba 100644
--- a/fpdfsdk/include/javascript/JS_Object.h
+++ b/fpdfsdk/include/javascript/JS_Object.h
@@ -10,6 +10,7 @@
 #include "../fsdk_define.h"  // For FX_UINT
 #include "../fsdk_mgr.h"  // For CPDFDoc_Environment
 #include "../fx_systemhandler.h"  // For IFX_SystemHandler
+#include "../jsapi/fxjs_v8.h"
 
 class CPDFSDK_PageView;
 class CJS_Object;