url: improve spec compliance of WHATWG URL

This patch contains the following changes:

url: make IPv4 parser more spec compliant

* Return int64_t from ParseNumber to prevent overflow for valid big numbers
* Don't throw when there are more than 4 parts (it cannot be an IP
address)
* Correctly interpret the address and don't always throw when there are
numbers > 255

Ref: https://url.spec.whatwg.org/#concept-ipv4-parser
Fixes: https://github.com/nodejs/node/issues/10306

url: percent encode fragment to follow spec change

Ref: https://github.com/whatwg/url/issues/150
Ref: https://github.com/whatwg/url/commit/373dbedbbf0596f723ce8a195923da98b698aeb0

url: fix URL#search setter

The check for empty string must be done before removing the leading '?'.

Ref: https://url.spec.whatwg.org/#dom-url-search

url: set port to null if an empty string is given

This is to follow a spec change.

Ref: https://github.com/whatwg/url/pull/113

url: fix parsing of paths with Windows drive letter

test: update WHATWG URL test fixtures

PR-URL: https://github.com/nodejs/node/pull/10317


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>