Pass CJS_Runtime to JS callbacks.

This is much more convenient, since only a fraction of them
need an IJS_EventContext, which can be obtained from the
CJS_Runtime.

Make GetCurrentEventContext() specific to CJS_Runtime, and
return the concrete type.  This saves a lot of casting.

Change-Id: If79a3bcbf44de513f3caace153099234cc313d47
Reviewed-on: https://pdfium-review.googlesource.com/2793
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
diff --git a/fpdfsdk/javascript/console.h b/fpdfsdk/javascript/console.h
index 1b6e9dd..a7e4d8e 100644
--- a/fpdfsdk/javascript/console.h
+++ b/fpdfsdk/javascript/console.h
@@ -17,19 +17,19 @@
   ~console() override;
 
  public:
-  bool clear(IJS_EventContext* cc,
+  bool clear(CJS_Runtime* pRuntime,
              const std::vector<CJS_Value>& params,
              CJS_Value& vRet,
              CFX_WideString& sError);
-  bool hide(IJS_EventContext* cc,
+  bool hide(CJS_Runtime* pRuntime,
             const std::vector<CJS_Value>& params,
             CJS_Value& vRet,
             CFX_WideString& sError);
-  bool println(IJS_EventContext* cc,
+  bool println(CJS_Runtime* pRuntime,
                const std::vector<CJS_Value>& params,
                CJS_Value& vRet,
                CFX_WideString& sError);
-  bool show(IJS_EventContext* cc,
+  bool show(CJS_Runtime* pRuntime,
             const std::vector<CJS_Value>& params,
             CJS_Value& vRet,
             CFX_WideString& sError);