Update code that hides site notice from search engines
While it might work for Bing, document.write() does not seem to be
enough to hide text from Google, as evident from a Google Search results
page that listed various pages from frr.wikipedia.org when searching
for the text of an active site notice
Additionally, core commit d861c6593a55 has broken document.write() logic
as the mediawiki.legacy.wikibits module now replaces it with its own code,
which can cause the site notice to end up at the bottom of the page (just
after #content, the last child of the body element at the time the script is
executed) instead of in its proper place (inside #siteNotice).
Instead of document.write(), use a temporary placeholder element and replace
it with parsed HTML directly using proper DOM methods.