I can think of two possible solutions:
- Change the search button into a button for fulltext search. This also fixes bug 24248. This should be quite easy: Change the name of the search-button into "fulltext" (and add a value="1", I don't know if this is necessary). This has the drawback that with disabled JS you need an extra click to get to an article as you always have to do a fulltext search.
- Always put two buttons (go and fulltext) into the HTML source and replace them via JS with the magnifying glass button.