Fix forgetting text when reloading extension because of Isolated Worlds
Fix forgetting text when reloading extension because of Isolated Worlds

During development, reloading the extension and reapplying it would previously replace header graphic text with "SBAHJ-static-canvas", because storing the text in a property on a DOM node it doesn't persist across extension versions the same way it doesn't cross over between extensions and the page, due to Isolated Worlds. Using an attribute, it goes into the shared DOM. (And might as well use a meaningful accessibility attribute.)

1j01/sbahjifier,1j01/sbahjifier