Add missing variables to Shell.

Samples/shell/include/ShellRenderInterfaceOpenGL.h

@@ -69,6 +69,10 @@ public:
 	virtual bool GenerateTexture(Rocket::Core::TextureHandle& texture_handle, const Rocket::Core::byte* source, const Rocket::Core::Vector2i& source_dimensions);
 	/// Called by Rocket when a loaded texture is no longer required.
 	virtual void ReleaseTexture(Rocket::Core::TextureHandle texture_handle);
+
+private:
+	int m_width;
+	int m_height;
 };
 
 #endif