Sync the URL constructor with the spec

Sync the URL constructor with the spec

https://url.spec.whatwg.org/#api

This changes the generated code, but ought not be observable, as any
call to `new URL(x, urlObject)` will now instead behaves as
`new URL(x, urlObject.toString())`.

BUG=460722
Committed: https://crrev.com/122f84f37a2ff865c3e76ff99280b24da8f2a2f9
Cr-Commit-Position: refs/heads/master@{#361342}

[philipj_slow, 2015-11-21 20:01:47]

The CQ bit was checked by philipj@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2015-11-21 20:02:04]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1464133002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1464133002/1

[philipj_slow, 2015-11-21 21:27:11]

philipj@opera.com changed reviewers:
+ bashi@chromium.org, jl@opera.com

[philipj_slow, 2015-11-21 21:27:11]

PTAL.

By getting rid of the URL type from the constructor, this interface will not be
affected by making [TypeChecking=Interface] the default, which I'm working on in
an unpublished and unfinished CL.

[commit-bot: I haz the power, 2015-11-22 04:51:53]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-11-22 04:51:53]

Dry run: This issue passed the CQ dry run.

[bashi, 2015-11-24 00:13:21]

bindings/ LGTM

[philipj_slow, 2015-11-24 07:43:15]

philipj@opera.com changed reviewers:
+ jochen@chromium.org

[philipj_slow, 2015-11-24 07:43:16]

Jochen, can you please review the non-bindings aspect of this, i.e. the API
change?

[haraken, 2015-11-24 08:12:45]

non-owner LGTM

[jochen (gone - plz use gerrit), 2015-11-24 13:07:16]

jochen@chromium.org changed reviewers:
+ haraken@chromium.org

[jochen (gone - plz use gerrit), 2015-11-24 13:07:16]

lgtm

[philipj_slow, 2015-11-24 13:51:46]

The CQ bit was checked by philipj@opera.com

[commit-bot: I haz the power, 2015-11-24 13:52:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1464133002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1464133002/1

[commit-bot: I haz the power, 2015-11-24 15:20:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-24 15:21:15]

Patchset 1 (id:??) landed as
https://crrev.com/122f84f37a2ff865c3e76ff99280b24da8f2a2f9
Cr-Commit-Position: refs/heads/master@{#361342}