[whatwg] WebWorkers and images

[Marijn Haverbeke]

> But if you could make it unreachable on the sending end then there would be no need to duplicate it, just to pass a reference to the worker, it would take about < 1 ns.

Yes, but the sender might have gotten this value from anywhere. All
other code using the value will have to know that it is going to be
invalidated, or it will use it and break. This complicates APIs and
leads to subtle bugs in a way comparable to C's memory management.