When the site title is inside an underscore template, syntax defined in `wp.template` like `{{ }}` is treated as special characters and will make Underscore treat it as data to be compiled/rendered.
Props pierlo, donmhico.
Fixes#46863.
git-svn-id: https://develop.svn.wordpress.org/trunk@46389 602fd350-edb4-49c9-b593-d223f7449a82