Dispatches event along path (root first, target last) in the three phases
of §72 — dispatchThreePhase with this module's listener keys.
Both key types propagate, so there is no targeted-only case to handle here.
An empty path dispatches nothing, which is what makes "nothing is focused" a
no-op rather than a special case at every call site.
Dispatches
eventalongpath(root first, target last) in the three phases of §72 — dispatchThreePhase with this module's listener keys.Both key types propagate, so there is no targeted-only case to handle here. An empty path dispatches nothing, which is what makes "nothing is focused" a no-op rather than a special case at every call site.