The String.localeCompare function is really slow, at least partially
because it creates a locale-aware collator object each time. So now,
when we can, we create and cache a locale-aware collator object.
However, this is not supported on most browsers, so we fall back to a
non-locale-aware comparison. This is not ideal, but for now we are
mostly working with English-speaking customers.
(imported from commit 51aa02e3b9fe4a0ef0cb084874fe26e91c57f65e)
96129b1cf0