[coro.generator.promise] Prevent erroneous hyphenation with \mbox

Author: tkoeppe

source/ranges.tex

@@ -15383,7 +15383,8 @@
 into which \tcode{g.range} is moved,
 whose member \tcode{await_ready} returns \tcode{false},
 whose member \tcode{await_suspend}
-pushes \tcode{g.range.\exposid{coroutine_}}
+% FIXME: The mbox prevents TeX from adding a bizarre hyphen after coroutine_.
+pushes \tcode{g.range.}\mbox{\exposid{coroutine_}}
 into \tcode{*x.\exposid{active_}}
 and resumes execution of the coroutine referred to
 by \tcode{g.range.\brk{}\exposid{coroutine_}}, and