Put back a fix that the PandaSE team happily but accidentally reverted

panda/src/gobj/shader.h

@@ -66,7 +66,7 @@ PUBLISHED:
   static PT(Shader) make(const ShaderLanguage &lang, const string &vertex, const string &fragment, const string &geometry = "");
 
   INLINE const Filename get_filename(const ShaderType &type = ST_none) const;
-  INLINE const string get_text(const ShaderType &type = ST_none) const;
+  INLINE const string &get_text(const ShaderType &type = ST_none) const;
   INLINE const bool get_error_flag() const;
   INLINE const ShaderLanguage get_language() const;