Support web-sys by default.

[jetli]

Currently this crate is using stdweb, and not supporting web-sys, can we support web-sys and use web-sys by default to avoid a stdweb dependency in a web-sys project, like what the Yew repo does.

[Stigjb]

There is a PR to support web-sys (#4), but the Yew repo has switched to wasm-logger in its examples (yewstack/yew#1181)