auto merge of #17035 : huonw/rust/moar-jquery, r=alexcrichton

Sometimes (e.g. on Rust CI) the "expand description" text of the
collapse toggle was displayed by default, when a page is first
loaded (even though the description is expanded), because some
Content-Security-Policy settings disable inline CSS.

Setting it the style with the `.css` method allows the output to be used
in more places.

diff --cc src/librustdoc/html/static/main.js
Simple merge