Remove the WEBCORE_NAVIGATOR_* defines

Remove the WEBCORE_NAVIGATOR_* defines

This is motivated by navigator.vendor, which Opera and multiple other
Chromium-based browsers have tweaked using this mechanism instead of
treating it like the long-frozen navigator.appName "Netscape".

There are cases of site compat issues caused by this, in a library
called UDM: http://www.udm4.com/demos/horizontal-relative-left.php

The "Intent to Implement and Ship: navigator.vendor as the empty string"
did not get the support required to align with Firefox and IE, so
freezing it in time as "Google Inc." is the second best thing.

It's unlikely that any of the other defines have been used.

History and discussion:
https://code.google.com/p/chromium/issues/detail?id=276813
https://www.w3.org/Bugs/Public/show_bug.cgi?id=27786
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/QrgyulnqvmE

BUG=276813, 454291
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=189436

[philipj_slow, 2015-02-02 15:24:05]

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

[philipj_slow, 2015-02-02 15:24:06]

PTAL

[pdr., 2015-02-03 18:58:52]

On 2015/02/02 at 15:24:06, philipj wrote:
> PTAL

LGTM! Thank you for sticking through this.

[philipj_slow, 2015-02-03 19:38:11]

The CQ bit was checked by philipj@opera.com

[commit-bot: I haz the power, 2015-02-03 19:38:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/896463002/1

[commit-bot: I haz the power, 2015-02-03 19:52:38]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=189436