Disable anchor ping attribute

[jumde]

From here: #13 (comment)

Description

This attribute has been known to track users cross domain

Steps to Reproduce

poc.html
<a href="https://www.w3schools.com/html" ping="<address_of_webserver>">Test</a>

1. Start a web server - python -m SimpleHTTPServer
2. Open poc.html and click on the link
3. Check the webserver logs

Actual result:

A request attempt when the link is clicked

Expected result:

No requests

Reproduces how often:

100%

Brave version (about:brave info)

Brave | 0.54.0 Chromium: 69.0.3497.32 (Official Build) dev (64-bit)

Reproducible on current release:

Yes

[bbondy]

Is this already disabled on browser-laptop?

[diracdeltas]

@bbondy yes it's disabled in muon

[btlechowski]

Verification passed on

Brave	0.55.5 Chromium: 70.0.3538.16 (Official Build) dev (64-bit)
Revision	16ed95b41bb05e565b11fb66ac33c660b721f778-refs/branch-heads/3538@{#306}
OS	Windows 7

[kjozwiak]

Went through verification using the following build under macOS 10.13.6 x64 - PASSED

Brave	0.55.10 Chromium: 70.0.3538.22 (Official Build) beta(64-bit)
Revision	ac9418ba9c3bd7f6baaffa0b055dfe147e0f8364-refs/branch-heads/3538@{#468}
OS	Mac OS X

Started a web server via python -m SimpleHTTPServer as specificed above. Created poc.html using the following:

<a href="https://www.w3schools.com/html" ping="http://localhost:8000//">Test</a>
<a href="https://www.apple.com/" ping="http://localhost:8000//">Test</a>
<a href="https://www.facebook.com/" ping="http://localhost:8000//">Test</a>

Opened http://localhost:8000/poc.html with 0.55.10 Chromium: 70.0.3538.22 and ensured that there weren't any pings being logged when clicking on the links. I also ensured that the same test case was failing under Chrome and the following pings were being logged:

127.0.0.1 - - [02/Oct/2018 20:09:48] code 501, message Unsupported method ('POST')
127.0.0.1 - - [02/Oct/2018 20:09:48] "POST // HTTP/1.1" 501 -

@LaurenWags also verified this on macOS 10.12.6 x64.

Verification passed on

Brave	0.55.10 Chromium: 70.0.3538.22 (Official Build) beta(64-bit)
Revision	ac9418ba9c3bd7f6baaffa0b055dfe147e0f8364-refs/branch-heads/3538@{#468}
OS	Linux