Fetch API backed by net crate #111

Implement the Fetch API, returning Promises and backed by the existing net crate (HTTP/1.1 + TLS).

Scope#

fetch() Global Function#

• fetch(url) — initiate HTTP GET, return Promise
• fetch(url, options) — support options:
  • method — HTTP method (GET, POST, PUT, DELETE, etc.)
  • headers — object or Headers instance
  • body — string body for POST/PUT
• Returns a Promise that resolves to a Response object
• Promise rejects on network errors (DNS failure, connection refused, TLS errors)

Response Object#

• response.ok — boolean, true if status 200-299
• response.status — HTTP status code (number)
• response.statusText — status text string
• response.headers — Headers object
• response.url — final URL after redirects
• response.text() — return Promise of response body
• response.json() — return Promise