Revert of Only execute default actions on trusted events.

Revert of Only execute default actions on trusted events. (patchset #6 id:100001 of https://codereview.chromium.org/1234613004/)

Reason for revert:
This change is suspected to be causing the following failures on the Mac builders:

https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.10/builds/1137
virtual/trustedeventsdefaultaction/fast/events/autoscroll.html
virtual/trustedeventsdefaultaction/fast/events/context-no-deselect.html
virtual/trustedeventsdefaultaction/fast/events/reveal-link-when-focused.html

http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.6/builds/42532
virtual/trustedeventsdefaultaction/fast/events/hit-test-cache-scrollbar-no-crash.html
virtual/pointerevent/fast/events/hit-test-cache-scrollbar-no-crash.html

https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.6%20%28dbg%29/builds/25157
fast/events/hit-test-cache-scrollbar-no-crash.html
virtual/pointerevent/fast/events/hit-test-cache-scrollbar-no-crash.html

Original issue's description:
> Only execute default actions on trusted events.
> 
> Add a RuntimeFeature to try out only allowing default actions to
> execute on trusted events.
> 
> This was previously tried in https://codereview.chromium.org/894913002 in
> a slightly different approach; this attempt is based on the isTrusted
> support. Also this time it is hidden behind a feature flag that
> isn't enabled as it has some web compatibility issues that needs to
> be quantified.
> 
> BUG=334015
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=199346

TBR=tkent@chromium.org,dtapuska@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=334015
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=199358

[alancutter (OOO until 2018), 2015-07-23 07:23:46]

Created Revert of Only execute default actions on trusted events.

[commit-bot: I haz the power, 2015-07-23 07:23:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1251043004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1251043004/1

[commit-bot: I haz the power, 2015-07-23 07:24:28]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=199358

[tkent, 2015-07-23 07:35:46]

lgtm

[dtapuska, 2015-07-23 13:12:53]

On 2015/07/23 07:35:46, tkent wrote:
> lgtm

This change won't fix the failing builders for 10.6; that was actually caused by
a different change of mine that added that layout test for mac. I'm working on a
fix for that.

As for the two other failures on 10.10; they are exception cases that should be
handled in the TestExpectations (as they are special cased there there for
Yosemite)