Implement Response.json if brought into spec.

[fabiancook]

A proof of concept can be seen in the feature/json branch

http-representation/src/response.ts

Lines 81 to 90 in 2478234

	static json(body: unknown, init?: ResponseInit) {
	const headers = new Headers(init?.headers);
	if (!headers.has("Content-Type")) {
	headers.set("Content-Type", "application/json");
	}
	return new Response(JSON.stringify(body), {
	...init,
	headers
	});
	}

Tracking whatwg/fetch/issues/1389 updates before merging.

[fabiancook]

Closed by #6