This function was mistyped; it was used in practice both accepting
string[] and number[], with the implementation taking advantage of the
fact that number.parseInt(<int>, 10) = <int>.
The only string[] callers were some overly defensive typing_data tests
that don't match the actual typing_data interface, so we remove the
string[] support and adjust the function's type, as well as those
tests.
This lets us simplify the long-ish ‘../../static/js’ paths, and will
remove the need for the ‘zrequire’ wrapper.
Signed-off-by: Anders Kaseorg <anders@zulip.com>