convert package to use wasm

This is the first in three pull requests to allow material to be compiled with wasm. To accomplish this, no package may use the gopherjs/js import. Instead, packages must use the gopherwasm/js import.

Because gopherwasm uses a different API, there is no way to modify these packages in a way that is backwards-compatible. However, gopherjs may eventually be abandoned, leaving this packaged orphaned, if it does not upgrade to wasm.