The annotations added in bug 1770158 only covered `StringToDouble`,
however as noted in the comments in that file, that isn't sufficient for
accurately parsing floating point numbers. This patch extends the
annotations to the single-precision floating point numbers as well and
will be used in the next part to clean up the implementation of
`nsTString::ToDouble`.
Differential Revision: https://phabricator.services.mozilla.com/D148304
97bb85687e