Possibility of a "global time source" for wasm targets

Having this option would be very nice for wasm32-unknown-unknown users, including myself, but the problem I see with it is that it only makes sense for wasm32-unknown-unknown users, given the status quo. wasm32-unknown-unknown having a stubbed-out std is an unusual situation; other targets generally either have a non-panicking std (even if, say, all fs operations return errors) or don’t have std at all. But perhaps there are other targets that can’t natively implement Instant that I don’t know of (the source code would take more work to make an exhaustive list out of) or new odd platforms will come along.

In any case, I don’t think this is a bad feature; I’m just unsure whether it has enough use cases for the Rust maintainers to be willing to add this complexity.