Remove all artifacts from reducethislist (#2646)
Remove all artifacts from reducethislist (#2646)

These are all imported directly from the src directory anyway, so they never
needed to be linked in the first place.

This is a significant reduction in the list.

Note that the artifacts themselves should still be moved out of runtime, but
that is for another PR.
PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs