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_Context.h b/fpdfsdk/include/javascript/JS_Context.h
index adb28cd..b35ba3b 100644
--- a/fpdfsdk/include/javascript/JS_Context.h
+++ b/fpdfsdk/include/javascript/JS_Context.h
@@ -7,6 +7,10 @@
 #ifndef _JS_CONTEXT_H_
 #define _JS_CONTEXT_H_
 
+#include "../../../core/include/fxcrt/fx_system.h"
+#include "../../../core/include/fxcrt/fx_string.h"
+#include "IJavaScript.h"
+
 class CJS_EventHandler;
 class CJS_Runtime;