Add missing tests network.spec.ts

[kblok]

network.spec.ts: Request.headers: should define Chrome as user agent header network.spec.ts: Request.headers: should define Firefox as user agent header network.spec.ts: Request.initiator: should return the initiator network.spec.ts: Response.buffer: should throw if the response does not have a body network.spec.ts: Response.statusText: handles missing status text network.spec.ts: Response.timing: returns timing information network.spec.ts: raw network headers: Same-origin set-cookie navigation network.spec.ts: raw network headers: Same-origin set-cookie subresource network.spec.ts: raw network headers: Cross-origin set-cookie