Add wxWebView::GetNativeBackend() method.

This allows to use platform-specific methods in user code.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72210 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/webview.h

@@ -179,6 +179,9 @@ public:
     virtual void Undo() = 0;
     virtual void Redo() = 0;
 
+    //Get the pointer to the underlying native engine.
+    virtual void* GetNativeBackend() const = 0;
+
 protected:
     virtual void DoSetPage(const wxString& html, const wxString& baseUrl) = 0;