[url] Clarification on URL.host setter's behavior (#75)

Raised at https://code.google.com/p/chromium/issues/detail?id=551901

It's confusing that the `host` getter gives us:
- "host:port" (for non-default port)
- "host" (for default port)

while the `host` setter handles input without port as a host-only modification operation.

The spec should include some notes to prevent misuse.

For the `host` setter, for example ... hard to phrase correctly ...:

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Note: Unlike the `host` getter, a value without a port does not mean implication of the default port. I.e. the `host` setter does nothing on _url_'s port if the given value does not contain a port.

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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/url/issues/75